Delta6-desaturase genes and uses thereof

ABSTRACT

The subject invention relates to the identification of genes involved in the desaturation of polyunsaturated fatty acids at carbon 6 (i.e., “Δ6-desaturase”). In particular, Δ6-desaturase may be utilized, for example, in the conversion of linoleic acid to γ-linolenic acid and in the conversion of α-linolenic acid stearidonic acid. The polyunsaturated fatty acids produced by use of the enzyme may be added to pharmaceutical compositions, nutritional compositions, animal feeds, as well as other products such as cosmetics.

BACKGROUND OF THE INVENTION

1. Technical Field

The subject invention relates to the identification and isolation ofgenes that encode an enzyme (i.e., Δ6-desaturase) involved in thesynthesis of polyunsaturated fatty acids and to uses thereof. Inparticular, Δ6-desaturase catalyzes the conversion of, for example,linoleic acid (C18:2n-6) to γ-linolenic acid (C18:3n-6) and α-linolenicacid (C18:3n-3) to stearidonic acid (C18:4n-3). The converted productsmay then be utilized as substrates in the production of otherpolyunsaturated fatty acids (PUFAs). The products or otherpolyunsaturated fatty acids may be added to pharmaceutical compositions,nutritional compositions, animal feeds as well as other products such ascosmetics.

2. Background Information

Desaturases are critical in the production of long-chain polyunsaturatedfatty acids that have many important functions. For example,polyunsaturated fatty acids (PUFAs) are important components of theplasma membrane of a cell, where they are found in the form ofphospholipids. They also serve as precursors to mammalian prostacyclins,eicosanoids, leukotrienes and prostaglandins.

Additionally, PUFAs are necessary for the proper development of thedeveloping infant brain as well as for tissue formation and repair. Inview of the biological significance of PUFAs, attempts are being made toproduce them, as well as intermediates leading to their production, inan efficient manner.

A number of enzymes, most notably desaturases and elongases, areinvolved in PUFA biosynthesis (see FIG. 1). For example, an elongase(elo) catalyzes the conversion of γ-linolenic acid (GLA) todihomo-γ-linolenic acid (DGLA) and of stearidonic acid (C18:4n-3) to(n-3)-eicosatetraenoic acid (C20:4n-3). Linoleic acid (LA, C18:2n-9, 12or C18:2n-6) is produced from oleic acid (C18:1-Δ9) by a Δ12-desaturase.GLA (C18:3n-6, 9, 12) is produced from linoleic acid by a Δ6-desaturase.

It must be noted that animals cannot desaturate beyond the Δ9 positionand therefore cannot convert oleic acid into linoleic acid. Likewise,γ-linolenic acid (ALA, C18:3n-9, 12, 15) cannot be synthesized bymammals. However, γ-linolenic acid can be converted to stearidonic acid(STA, C18:4n-6, 9, 12, 15) by a Δ6-desaturase (see PCT publication WO96/13591 and The FASEB Journal, Abstracts, Part I, Abstract 3093, pageΔ532 (Experimental Biology 98, San Francisco, Calif., Apr. 18-22, 1998);see also U.S. Pat. No. 5,552,306), followed by elongation to(n-3)-eicosatetraenoic acid (C20:4n-8, 11, 14, 17) in mammals and algae.This polyunsaturated fatty acid (i.e., C20:4n-8, 11, 14, 17) can then beconverted to eicosapentaenoic acid (EPA, C20:5n-5, 8, 11, 14, 17) by aΔ5-desaturase. EPA can then, in turn, be converted toω3-docosapentaenoic acid (C22:5n-3) by an elongase.

Other eukaryotes, including fungi and plants, have enzymes whichdesaturate at carbon 12 (see PCT publication WO 94/11516 and U.S. Pat.No. 5,443,974) and carbon 15 (see PCT publication WO 93/11245). Themajor polyunsaturated fatty acids of animals therefore are eitherderived from diet and/or from desaturation and elongation of linoleicacid or γ-linolenic acid. In view of these difficulties, it is ofsignificant interest to isolate genes involved in PUFA synthesis fromspecies that naturally produce these fatty acids and to express thesegenes in a microbial, plant, or animal system which can be altered toprovide production of commercial quantities of one or more PUFAs.

In view of the above discussion, there is a definite need for theΔ6-desaturase enzyme, the respective genes encoding this enzyme, as wellas recombinant methods of producing this enzyme. Additionally, a needexists for oils containing levels of PUFAs beyond those naturallypresent as well as those enriched in novel PUFAs. Such oils can only bemade by isolation and expression of the Δ6-desaturase genes.

All U.S. patents and publications referred to herein are herebyincorporated in their entirety by reference.

SUMMARY OF THE INVENTION

The present invention includes an isolated nucleotide sequence orfragment thereof encoding a polypeptide having desaturase activity,wherein said polypeptide comprises an amino acid sequence having atleast 90% amino acid sequence identity to an amino acid sequenceselected from the group consisting of SEQ ID NO:2, SEQ ID NO:4, SEQ IDNO:6 and SEQ ID NO:8.

Additionally, the present invention encompasses an isolated nucleic acidsequence or fragment thereof comprising, or complementary to, anucleotide sequence having at least 90% nucleotide sequence identity toa nucleotide sequence selected from the group consisting of SEQ ID NO:1,SEQ ID NO:3, SEQ ID NO:5 and SEQ ID NO:7.

The nucleotide sequences described above encode a functionally activedesaturase that utilizes a monounsaturated or polyunsaturated fatty acidas a substrate. The nucleotide sequences may be derived for example,from Delacroixia coronatus. The present invention also includes purifiedproteins and fragments thereof encoded by the above-referencednucleotide sequences.

In particular, the present invention also includes a purifiedpolypeptide which desaturates polyunsaturated fatty acids at carbon 6and has an amino acid sequence having at least 90% amino acid identityto an amino acid sequence selected from the group consisting of SEQ IDNO:2, SEQ ID NO:4, SEQ ID NO:6 and SEQ ID NO:8.

Additionally, the present invention includes a method of producing adesaturase comprising the steps of: isolating a nucleotide sequencecomprising or complementary to a nucleotide sequence encoding apolypeptide comprising an amino acid sequence having at least 90%identity to an amino acid sequence of SEQ ID NO:2, SEQ ID NO:4, SEQ IDNO:6 and SEQ ID NO:8; constructing a vector comprising: i) the isolatednucleotide sequence operably linked to ii) a promoter; and introducingsaid vector into a host cell for a time and under conditions sufficientfor expression of the desaturase. The host cell may be, for example, aeukaryotic cell or a prokaryotic cell. In particular, the prokaryoticcell may be, for example, E. coli, cyanobacteria or B. subtilis. Theeukaryotic cell may be, for example, a mammalian cell, an insect cell, aplant cell or a fungal cell (e.g., a yeast cell such as Saccharomycescerevisiae, Saccharomyces carlsbergensis, Candida spp., Lipomycesstarkey, Yarrowia lipolytica, Kluyveromyces spp., Hansenula spp.,Trichoderma spp. or Pichia spp.). Other fungal hosts such as Rizopusspp., Aspergillus spp. and Mucor spp. may also be utilized.

Moreover, the present invention also includes a vector comprising: anisolated nucleotide sequence comprising or complementary to a nucleotidesequence encoding a polypeptide having an amino acid sequence having atleast 90% amino acid identity to an amino acid sequence selected fromthe group consisting of SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6 and SEQ IDNO:8, operably linked to a regulatory sequence (e.g., a promoter). Theinvention also includes a host cell comprising this vector. The hostcell may be, for example, a eukaryotic cell or a prokaryotic cell.Suitable eukaryotic cells and prokaryotic cells are as defined above.

Additionally, the present invention includes an isolated plant cell,plant or plant tissue comprising the above vector, wherein expression ofthe nucleotide sequence of the vector results in production of apolyunsaturated fatty acid by the plant cell, plant or plant tissue. Thepolyunsaturated fatty acid may be, for example, selected from the groupconsisting of γ-linolenic acid or stearidonic acid. The invention alsoincludes one or more plant oils or acids expressed by the above plantcell, plant or plant tissue.

Additionally, the present invention also encompasses a transgenic plantcomprising the above vector, wherein expression of the nucleotidesequence of the vector results in production of a polyunsaturated fattyacid in seeds of the transgenic plant.

The present invention also includes a method (“first method”) forproducing a polyunsaturated fatty acid comprising the steps of:isolating a nucleic acid sequence comprising or complementary to anucleotide sequence encoding a polypeptide comprising an amino acidsequence having at least 90% amino acid sequence identity to an aminoacid sequence selected from the group consisting of SEQ ID NO:2, SEQ IDNO:4, SEQ ID NO:6 and SEQ ID NO:8 or 90% nucleotide sequence identity toa nucleotide sequence selected from the group consisting of SEQ ID NO:1,SEQ ID NO:3, SEQ ID NO:5 and SEQ ID NO:7; constructing a vectorcomprising the isolated nucleotide sequence; introducing the vector intoa host cell for a time and under conditions sufficient for expression ofΔ6-desaturase; and exposing the expressed Δ6-desaturase to a substratepolyunsaturated fatty acid in order to convert the substrate to aproduct polyunsaturated fatty acid. The substrate polyunsaturated fattyacid may be, for example, linolenic acid or α-linolenic acid, and theproduct polyunsaturated fatty acid may be, for example, γ-linolenic acidor stearidonic acid, respectively. This method may further comprise thestep of exposing the product polyunsaturated fatty acid to anotherenzyme (e.g., an elongase) in order to convert the productpolyunsaturated fatty acid to another polyunsaturated fatty acid (i.e.,“second” method). In this method containing the additional step (i.e.,“second” method), the product polyunsaturated fatty acid may be, forexample, γ-linolenic acid or stearidonic acid and the “another”polyunsaturated fatty acid may be, for example, dihomo-γ-linolenic acidor eicosatetraenoic acid.

Also, the present invention includes a method of producing apolyunsaturated fatty acid comprising the steps of: exposing a substratemonounsaturated or polyunsaturated fatty acid to an enzyme (e.g., anelongase or desaturase) in order to convert the substrate to a productpolyunsaturated fatty acid; and exposing the product polyunsaturatedfatty acid to a Δ6-desaturase comprising the amino acid sequenceselected from the group consisting of SEQ ID NO:2, SEQ ID NO:4, SEQ IDNO:6 and SEQ ID NO:8, in order to convert the product polyunsaturatedfatty acid to a final product polyunsaturated fatty acid.

For example, a substrate polyunsaturated fatty acid (e.g., linoleicacid) may be exposed to a ω3-desaturase (e.g., Δ15-desaturase) in orderto convert the substrate to a “product” polyunsaturated fatty acid(e.g., α-linolenic acid). The product polyunsaturated fatty acid maythen be converted to a “final” product polyunsaturated fatty acid (e.g.,stearidonic acid) by exposure to the Δ6-desaturase of the presentinvention (see FIG. 1). Alternatively, a substrate monounsaturated fattyacid such as oleic acid may be exposed to a desaturase (e.g.,Δ12-desaturase) in order to convert the substrate to a productpolyunsaturated fatty acid such as linoleic acid. The productpolyunsaturated fatty acid may then be converted to the final productpolyunsaturated fatty acid, γ-linolenic acid by exposure to theΔ6-desaturase of the present invention. Thus, the Δ6-desaturase isutilized in the last step of the method in order to create the “final”desired product. As another example, one may expose linoleic acid to aΔ6-desaturase in order to create γ-linolenic acid (GLA), and then exposethe GLA to an elongase to create dihomo-γ-linolenic acid (DGLA) and thenexpose DGLA to a Δ5-desaturase in order to create arachidonic acid (AA).The AA may then be exposed to an elongase in order to convert it toadrenic acid. Finally, the adrenic acid may be exposed to Δ4-desaturasein order to convert it to ω6-docosapentaenoic acid (see FIG. 1). Thus,the method involves the utilization of a linoleic acid substrate and aseries of desaturase and elongase enzymes, in addition to theΔ6-desaturase, in order to arrive at the final product. (Possiblesubstrates include those shown in FIG. 1, for example, linoleic acid andα-linolenic acid.)

The present invention also encompasses a composition comprising at leastone polyunsaturated fatty acid selected from the group consisting of the“product” polyunsaturated fatty acid produced according to the methodsdescribed above and the “another” polyunsaturated fatty acid producedaccording to the methods described above. The product polyunsaturatedfatty acid may be, for example, γ-linolenic acid or stearidonic acid.The another polyunsaturated fatty acid may be, for example,dihomo-γ-linolenic acid or eicosatetraenoic acid.

Additionally, the present invention encompasses a method of preventingor treating a condition caused by insufficient intake of polyunsaturatedfatty acids comprising administering to the patient the compositionabove in an amount sufficient to effect prevention or treatment.

Moreover, the present invention also includes a further method forproducing a polyunsaturated fatty acid. This method comprises the stepsof: a) isolating a nucleic acid sequence comprising or complementary toa nucleotide sequence: i) encoding a polypeptide comprising an aminoacid sequence having at least 90% identity to an amino acid sequenceselected from the group consisting of SEQ ID NO:2, SEQ ID NO:4, SEQ IDNO:6 and SEQ ID NO:8 or ii) having at least 90% identity to a nucleotidesequence selected from the group consisting of SEQ ID NO:1, SEQ ID NO:3,SEQ ID NO:5 and SEQ ID NO:7; b) constructing a vector comprising: i) theisolated nucleotide sequence, ii) an isolated nucleotide sequenceencoding an elongase and iii) an isolated nucleotide sequence encoding aΔ5-desaturase; c) introducing the vector into a host cell for a time andunder conditions sufficient for expression of the Δ6-desaturase, theelongase and said Δ5-desaturase; and d) exposing the expressedΔ6-desaturase, the expressed elongase and the expressed Δ5-desaturase toa substrate polyunsaturated fatty acid in order to convert the substrateto a product polyunsaturated fatty acid, the product polyunsaturatedfatty acid to another polyunsaturated fatty acid and the anotherpolyunsaturated fatty acid to a final product polyunsaturated fattyacid. For example, the substrate polyunsaturated fatty acid may belinoleic acid, the product polyunsaturated fatty acid may be γ-linolenicacid, the another polyunsaturated fatty acid may be dihomo-γ-linolenicacid and the final product polyunsaturated fatty acid may be arachidonicacid. Alternatively, the substrate polyunsaturated fatty acid may beα-linolenic acid, the product polyunsaturated fatty acid may bestearidonic acid, the another polyunsaturated fatty acid may beeicosatetraenoic acid and the final product polyunsaturated fatty acidmay be eicosapentaenoic acid.

Additionally, the present invention includes an isolated nucleic acidsequence or fragment thereof which hybridizes, under moderate or highstringency conditions, to a nucleic acid sequence selected from thegroup consisting of SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:5 and SEQ IDNO:7.

The present invention also encompasses an isolated nucleic acid orfragment thereof, which hybridizes, under moderate or high stringencyconditions, to an isolated nucleic acid sequence encoding a polypeptidehaving desaturase activity, wherein the amino acid sequence of saidpolypeptide has at least 90% identity to an amino acid sequence selectedfrom the group consisting of SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6 andSEQ ID NO:8.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the fatty acid biosynthetic pathway and the role ofΔ6-desaturase in this pathway. Major pathway intermediates found in thetotal lipid profile of Delacroixia are boxed.

FIG. 2 illustrates the consensus nucleotide sequence of the putativedesaturase from Delacroixia (SEQ ID NO:1), obtained by the alignment ofthree separate overlapping clones.

FIG. 3 illustrates the consensus amino acid sequence of the putativedesaturase from Delacroixia (SEQ ID NO:2), obtained by the alignment ofthree separate overlapping clones.

FIG. 4 illustrates the GAP alignment of the translated amino acidsequence of FIG. 3 (SEQ ID NO:2) and the Mortierella alpinaΔ6-desaturase (SEQ ID NO:40).

FIG. 5 illustrates the comparison of the location of the various ‘ATG’start codons (bold, underlined) created in the putative desaturase genesequence (Del-D6) from Delacroixia (Consensus=SEQ ID NO:41; pRDC8=SEQ IDNO:42; pRDC10=SEQ ID NO:43; pRDC12=SEQ ID NO:44).

FIG. 6 illustrates the nucleotide sequence of the putative desaturasegene from Delacroixia coronatus ATCC 28565, in construct pRDC8, with thedesignated start site underlined (SEQ ID NO:3).

FIG. 7 illustrates the putative amino acid sequence of the Δ6-desaturasegene (SEQ ID NO:4) from Delacroixia coronatus ATCC 28565, in constructpRDC8.

FIG. 8 illustrates the nucleotide sequence of the putative desaturasegene (SEQ ID NO:5) from Delacroixia coronatus ATCC 28565, in constructpRDC10, with the designated start site underlined.

FIG. 9 illustrates the putative amino acid sequence of the Δ6-desaturasegene (SEQ ID NO:6) from Delacroixia coronatus ATCC 28565, in constructpRDC10.

FIG. 10 illustrates the nucleotide sequence of Del-D6 (SEQ ID NO:7), theΔ6-desaturase from Delacroixia coronatus ATCC 28565, in constructpRDC12.

FIG. 11 illustrates the putative amino acid sequence of Del-D6 (SEQ IDNO:8), the Δ6-desaturase from Delacroixia coronatus ATCC 28565, inconstruct pRDC12.

FIG. 12 illustrates the alignment of the putative amino acid sequenceencoded by Del-D6 (in pRDC12)(see SEQ ID NO:8) (i.e., the Δ6-desaturasefrom Delacroixia coronatus ATCC 28565) and the Mortierella alpinaΔ6-desaturase (see SEQ ID NO:40).

FIG. 13 illustrates the alignment of the putative amino acid sequenceencoded by Del-D6 (in PRDC12) with known Δ6-desaturase sequences fromMortierella alpina (Accession #AAF08685), Phaeodactylum tricornatum(Accession #AAL92563), Rhizopus oryzae (Accession #AAS93682), Pythiumirregulare (Accession # AAL13310), and Mucor circinelloides (Accession #BAB69055). Identical residues are underlined and the conservedhistidine-box motifs as well as the conserved cytochrome b₅ domain areboxed.

DETAILED DESCRIPTION OF THE INVENTION

The subject invention relates to the nucleotide and translated aminoacid sequences of the Δ6-desaturase genes derived from the fungusDelacroixia coronata. Furthermore, the subject invention also includesuses of the genes and of the enzymes encoded by this gene. For example,the genes and encoded, corresponding enzymes may be used in theproduction of polyunsaturated fatty acids such as, for instance,γ-linolenic acid and stearidonic acid which may be added topharmaceutical compositions, nutritional compositions and to othervaluable products.

The Δ6-Desaturase Genes and Enzymes Encoded Thereby

As noted above, the enzymes encoded by the Δ6-desaturase genes of thepresent invention are essential in the production of polyunsaturatedfatty acids. FIG. 2 illustrates the consensus nucleotide sequence (SEQID NO:1) of the putative Δ6-desaturase from Delacroixia coronatus, andFIG. 3 illustrates the consensus amino acid sequence (SEQ ID NO:2) ofthe putative Δ6-desaturase from Delacroixia coronatus. The nucleotidesequences of the isolated Delacroixia coronatus Δ6-desaturase genes,which differed based upon the plasmid created (see Example II), areshown in FIG. 6 (SEQ ID NO:3), FIG. 8 (SEQ ID NO:5) and FIG. 10 (SEQ IDNO:7), and the amino acid sequences of the corresponding purifiedproteins are shown in FIG. 7 (SEQ ID NO:4), FIG. 9 (SEQ ID NO:6) andFIG. 11 (SEQ ID NO:8), respectively.

It should be noted that the present invention also encompasses isolatednucleotide sequences (and the corresponding encoded proteins) havingsequences comprising, corresponding to, identical to, or complementaryto at least about 70%, preferably at least about 80%, and morepreferably at least about 90% identity to SEQ ID NO:1, SEQ ID NO:3, SEQID NO:5 or SEQ ID NO:7. (All integers (and portions thereof) between 70%and 100% are also considered to be within the scope of the presentinvention with respect to percent identity.) Such sequences may bederived from any source, either isolated from a natural source, orproduced via a semi-synthetic route, or synthesized de novo. Inparticular, such sequences may be isolated or derived from sources otherthan described in the examples (e.g., bacteria, fungus, algae, C.elegans, mouse or human).

Furthermore, the present invention also encompasses fragments andderivatives of the nucleic acid sequences of the present invention(i.e., SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:5 and SEQ ID NO:7), as wellas of the sequences derived from other sources, and having theabove-described complementarity, identity or correspondence. Functionalequivalents of the above full length sequences and fragments (i.e.,sequences having Δ6-desaturase activity, as appropriate) are alsoencompassed by the present invention.

For purposes of the present invention, a “fragment” of a nucleotidesequence is defined as a contiguous sequence of approximately at least6, preferably at least about 8, more preferably at least about 10nucleotides, and even more preferably at least about 15 nucleotidescorresponding to a region of the specified nucleotide sequence.

The invention also includes a purified polypeptide which desaturatespolyunsaturated fatty acids at the carbon 6 position and has at leastabout 70% amino acid similarity or identity, preferably at least about80% amino acid similarity or identity and more preferably at least about90% amino acid similarity or identity to the amino acid sequences of SEQID NO:2, SEQ ID NO:4, SEQ ID NO:6 or SEQ ID NO:8 of the above-notedproteins which are, in turn, encoded by the above-described nucleotidesequences.

The term “identity” refers to the relatedness of two sequences on anucleotide-by-nucleotide basis over a particular comparison window orsegment. Thus, identity is defined as the degree of sameness,correspondence or equivalence between the same strands (either sense orantisense) of two DNA segments (or two amino acid sequences).“Percentage of sequence identity” is calculated by comparing twooptimally aligned sequences over a particular region, determining thenumber of positions at which the identical base or amino acid occurs inboth sequences in order to yield the number of matched positions,dividing the number of such positions by the total number of positionsin the segment being compared and multiplying the result by 100. Optimalalignment of sequences may be conducted by the algorithm of Smith &Waterman, Appl. Math. 2:482 (1981), by the algorithm of Needleman &Wunsch, J. Mol. Biol. 48:443 (1970), by the method of Pearson & Lipman,Proc. Natl. Acad. Sci. (USA) 85:2444 (1988) and by computer programswhich implement the relevant algorithms (e.g., Clustal Macaw Pileup(http://cmgm.stanford.edu/biochem218/11Multiple.pdf; Higgins et al.,CABIOS. 5L151-153 (1989)), FASTDB (Intelligenetics), BLAST (NationalCenter for Biomedical Information; Altschul et al., Nucleic AcidsResearch 25:3389-3402 (1997)), PILEUP (Genetics Computer Group, Madison,Wis.) or GAP, BESTFIT, FASTA and TFASTA (Wisconsin Genetics SoftwarePackage Release 7.0, Genetics Computer Group, Madison, Wis.). (See U.S.Pat. No. 5,912,120.)

For purposes of the present invention, “complementarity is defined asthe degree of relatedness between two DNA segments. It is determined bymeasuring the ability of the sense strand of one DNA segment tohybridize with the anti-sense strand of the other DNA segment, underappropriate conditions, to form a double helix. A “complement” isdefined as a sequence which pairs to a given sequence based upon thecanonic base-pairing rules. For example, a sequence A-G-T in onenucleotide strand is “complementary” to T-C-A in the other strand.

In the double helix, adenine appears in one strand, thymine appears inthe other strand. Similarly, wherever guanine is found in one strand,cytosine is found in the other. The greater the relatedness between thenucleotide sequences of two DNA segments, the greater the ability toform hybrid duplexes between the strands of the two DNA segments.

“Similarity” between two amino acid sequences is defined as the presenceof a series of identical as well as conserved amino acid residues inboth sequences. The higher the degree of similarity between two aminoacid sequences, the higher the correspondence, sameness or equivalenceof the two sequences. (“Identity between two amino acid sequences isdefined as the presence of a series of exactly alike or invariant aminoacid residues in both sequences.) The definitions of “complementarity”,“identity” and “similarity” are well known to those of ordinary skill inthe art.

“Encoded by” refers to a nucleic acid sequence which codes for apolypeptide sequence, wherein the polypeptide sequence or a portionthereof contains an amino acid sequence of at least 3 amino acids, morepreferably at least 8 amino acids, and even more preferably at least 15amino acids from a polypeptide encoded by the nucleic acid sequence.

The present invention also encompasses an isolated nucleotide sequencewhich encodes a PUFA having desaturase activity (i.e., Δ6-desaturaseactivity) and that is hybridizable, under moderately stringentconditions, to a nucleic acid having a nucleotide sequence comprising orcomplementary to the nucleotide sequences described above (see SEQ IDNO:1, SEQ ID NO:3, SEQ ID NO:5 and SEQ ID NO:7). A nucleic acid moleculeis “hybridizable” to another nucleic acid molecule when asingle-stranded form of the nucleic acid molecule can anneal to theother nucleic acid molecule under the appropriate conditions oftemperature and ionic strength (see Sambrook et al., “Molecular Cloning:A Laboratory Manual, Second Edition (1989), Cold Spring HarborLaboratory Press, Cold Spring Harbor, N.Y.)). The conditions oftemperature and ionic strength determine the “stringency” of thehybridization.

The term “hybridization” as used herein is generally used to meanhybridization of nucleic acids at appropriate conditions of stringencyas would be readily evident to those skilled in the art depending uponthe nature of the probe sequence and target sequences. Conditions ofhybridization and washing are well known in the art, and the adjustmentof conditions depending upon the desired stringency by varyingincubation time, temperature and/or ionic strength of the solution arereadily accomplished. See, for example, Sambrook, J. et al., MolecularCloning: A Laboratory Manual, 2nd edition, Cold spring harbor Press,Cold Spring harbor, N.Y., 1989, as noted above and incorporated hereinby reference. (See also Short Protocols in Molecular Biology, ed.Ausubel et al. and Tijssen, Techniques in Biochemistry and MolecularBiology-Hybridization with Nucleic Acid Probes, “Overview of principlesof hybridization and the strategy of nucleic acid assays” (1993), bothincorporated herein by reference.) Specifically, the choice ofconditions is dictated by the length of the sequences being hybridized,in particular, the length of the probe sequence, the relative G-Ccontent of the nucleic acids and the amount of mismatches to bepermitted. Low stringency conditions are preferred when partialhybridization between strands that have lesser degrees ofcomplementarity is desired. When perfect or near perfect complementarityis desired, high stringency conditions are preferred. For typical highstringency conditions, the hybridization solution contains 6×S.S.C.,0.01 M EDTA, 1× Denhardt's solution and 0.5% SDS. Hybridization iscarried out at about 68 degrees Celsius for about 3 to 4 hours forfragments of cloned DNA and for about 12 to about 16 hours for totaleukaryotic DNA. For moderate stringencies, one may utilize filterpre-hybridizing and hybridizing with a solution of 3× sodium chloride,sodium citrate (SSC), 50% formamide (0.1 M of this buffer at pH 7.5) and5× Denhardt's solution. One may then pre-hybridize at 37 degrees Celsiusfor 4 hours, followed by hybridization at 37 degrees Celsius with anamount of labeled probe equal to 3,000,000 cpm total for 16 hours,followed by a wash in 2×SSC and 0.1% SDS solution, a wash of 4 times for1 minute each at room temperature and 4 times at 60 degrees Celsius for30 minutes each. Subsequent to drying, one exposes to film. For lowerstringencies, the temperature of hybridization is reduced to about 12degrees Celsius below the melting temperature (T_(m)) of the duplex. TheT_(m) is known to be a function of the G-C content and duplex length aswell as the ionic strength of the solution.

“Hybridization” requires that two nucleic acids contain complementarysequences. However, depending on the stringency of the hybridization,mismatches between bases may occur. As noted above, the appropriatestringency for hybridizing nucleic acids depends on the length of thenucleic acids and the degree of complementation. Such variables are wellknown in the art. More specifically, the greater the degree ofsimilarity or homology between two nucleotide sequences, the greater thevalue of Tm for hybrids of nucleic acids having those sequences. Forhybrids of greater than 100 nucleotides in length, equations forcalculating Tm have been derived (see Sambrook et al., supra). Forhybridization with shorter nucleic acids, the position of mismatchesbecomes more important, and the length of the oligonucleotide determinesits specificity (see Sambrook et al., supra).

As used herein, an “isolated nucleic acid fragment or sequence” is apolymer of RNA or DNA that is single- or double-stranded, optionallycontaining synthetic, non-natural or altered nucleotide bases. Anisolated nucleic acid fragment in the form of a polymer of DNA may becomprised of one or more segments of cDNA, genomic DNA or synthetic DNA.(A “fragment” of a specified polynucleotide refers to a polynucleotidesequence which comprises a contiguous sequence of approximately at leastabout 6 nucleotides, preferably at least about 8 nucleotides, morepreferably at least about 10 nucleotides, and even more preferably atleast about 15 nucleotides, and most preferable at least about 25nucleotides identical or complementary to a region of the specifiednucleotide sequence.) Nucleotides (usually found in their5′-monophosphate form) are referred to by their single letterdesignation as follows: “A” for adenylate or deoxyadenylate (for RNA orDNA, respectively), “C” for cytidylate or deoxycytidylate, “G” forguanylate or deoxyguanylate, “U” for uridylate, “T” fordeoxythymidylate, “R” for purines (A or G), “Y” for pyrimidines (C orT), “K” for G or T, “H” for A or C or T, “I” for inosine, and “N” forany nucleotide.

The terms “fragment or subfragment that is functionally equivalent” and“functionally equivalent fragment or subfragment” are usedinterchangeably herein. These terms refer to a portion or subsequence ofan isolated nucleic acid fragment in which the ability to alter geneexpression or produce a certain phenotype is retained whether or not thefragment or subfragment encodes an active enzyme. For example, thefragment or subfragment can be used in the design of chimeric constructsto produce the desired phenotype in a transformed plant. Chimericconstructs can be designed for use in co-suppression or antisense bylinking a nucleic acid fragment or subfragment thereof, whether or notit encodes an active enzyme, in the appropriate orientation relative toa plant promoter sequence.

The terms “homology”, “homologous”, “substantially similar” and“corresponding substantially” are used interchangeably herein. Theyrefer to nucleic acid fragments wherein changes in one or morenucleotide bases does not affect the ability of the nucleic acidfragment to mediate gene expression or produce a certain phenotype.These terms also refer to modifications of the nucleic acid fragments ofthe instant invention such as deletion or insertion of one or morenucleotides that do not substantially alter the functional properties ofthe resulting nucleic acid fragment relative to the initial, unmodifiedfragment. It is therefore understood, as those skilled in the art willappreciate, that the invention encompasses more than the specificexemplary sequences.

“Gene” refers to a nucleic acid fragment that expresses a specificprotein, including regulatory sequences preceding (5′ non-codingsequences) and following (3′ non-coding sequences) the coding sequence.

“Native gene” refers to a gene as found in nature with its ownregulatory sequences. In contrast, “chimeric construct” refers to acombination of nucleic acid fragments that are not normally foundtogether in nature. Accordingly, a chimeric construct may compriseregulatory sequences and coding sequences that are derived fromdifferent sources, or regulatory sequences and coding sequences derivedfrom the same source, but arranged in a manner different than thatnormally found in nature. (The term “isolated” means that the sequenceis removed from its natural environment.)

A “foreign” gene refers to a gene not normally found in the hostorganism, but that is introduced into the host organism by genetransfer. Foreign genes can comprise native genes inserted into anon-native organism, or chimeric constructs. A “transgene” is a genethat has been introduced into the genome by a transformation procedure.

“Coding sequence” refers to a DNA sequence that codes for a specificamino acid sequence. “Regulatory sequences” refer to nucleotidesequences located upstream (5′ non-coding sequences), within, ordownstream (3′ non-coding sequences) of a coding sequence, and whichinfluence the transcription, RNA processing or stability, or translationof the associated coding sequence. Regulatory sequences may include, butare not limited to, promoters, translation leader sequences, introns,and polyadenylation recognition sequences.

“Promoter” refers to a DNA sequence capable of controlling theexpression of a coding sequence or functional RNA. The promoter sequenceconsists of proximal and more distal upstream elements, the latterelements often referred to as enhancers. Accordingly, an “enhancer” is aDNA sequence which can stimulate promoter activity and may be an innateelement of the promoter or a heterologous element inserted to enhancethe level or tissue-specificity of a promoter. Promoter sequences canalso be located within the transcribed portions of genes, and/ordownstream of the transcribed sequences. Promoters may be derived intheir entirety from a native gene, or be composed of different elementsderived from different promoters found in nature, or even comprisesynthetic DNA segments. It is understood by those skilled in the artthat different promoters may direct the expression of a gene indifferent tissues or cell types, or at different stages of development,or in response to different environmental conditions. Promoters whichcause a gene to be expressed in most host cell types at most times arecommonly referred to as “constitutive promoters”. New promoters ofvarious types useful in plant cells are constantly being discovered;numerous examples may be found in the compilation by Okamuro andGoldberg, Biochemistry of Plants 15:1-82 (1989). It is furtherrecognized that since in most cases the exact boundaries of regulatorysequences have not been completely defined, DNA fragments of somevariation may have identical promoter activity.

An “intron” is an intervening sequence in a gene that does not encode aportion of the protein sequence. Thus, such sequences are transcribedinto RNA but are then excised and are not translated. The term is alsoused for the excised RNA sequences. An “exon” is a portion of the genesequence that is transcribed and is found in the mature messenger RNAderived from the gene, but is not necessarily a part of the sequencethat encodes the final gene product.

The “translation leader sequence” refers to a DNA sequence locatedbetween the promoter sequence of a gene and the coding sequence. Thetranslation leader sequence is present in the fully processed mRNAupstream of the translation start sequence. The translation leadersequence may affect processing of the primary transcript to mRNA, mRNAstability or translation efficiency. Examples of translation leadersequences have been described (Turner, R. and Foster, G. D. (1995)Molecular Biotechnology 3:225).

The “3′ non-coding sequences” refer to DNA sequences located downstreamof a coding sequence and include polyadenylation recognition sequencesand other sequences encoding regulatory signals capable of affectingmRNA processing or gene expression. The polyadenylation signal isusually characterized by affecting the addition of polyadenylic acidtracts to the 3′ end of the mRNA precursor. The use of different 3′non-coding sequences is exemplified by Ingelbrecht et al., Plant Cell1:671-680 (1989).

“RNA transcript” refers to the product resulting from RNApolymerase-catalyzed transcription of a DNA sequence. When the RNAtranscript is a perfect complementary copy of the DNA sequence, it isreferred to as the primary transcript or it may be a RNA sequencederived from post-transcriptional processing of the primary transcriptand is referred to as the mature RNA. “Messenger RNA (mRNA)” refers tothe RNA that is without introns and that can be translated into proteinby the cell. “cDNA” refers to a DNA that is complementary to andsynthesized from a mRNA template using the enzyme reverse transcriptase.The cDNA can be single-stranded or converted into the double-strandedform using the Klenow fragment of DNA polymerase I. “Sense” RNA refersto RNA transcript that includes the mRNA and can be translated intoprotein within a cell or in vitro. “Antisense RNA” refers to an RNAtranscript that is complementary to all or part of a target primarytranscript or mRNA and that blocks the expression of a target gene (U.S.Pat. No. 5,107,065). The complementarity of an antisense RNA may be withany part of the specific gene transcript, i.e., at the 5′ non-codingsequence, 3′ non-coding sequence, introns, or the coding sequence.“Functional RNA” refers to antisense RNA, ribozyme RNA, or other RNAthat may not be translated but yet has an effect on cellular processes.The terms “complement” and “reverse complement” are used interchangeablyherein with respect to mRNA transcripts, and are meant to define theantisense RNA of the message.

The term “endogenous RNA” refers to any RNA which is encoded by anynucleic acid sequence present in the genome of the host prior totransformation with the recombinant construct of the present invention,whether naturally-occurring or non-naturally occurring, i.e., introducedby recombinant means, mutagenesis, etc.

The term “non-naturally occurring” means artificial, not consistent withwhat is normally found in nature.

The term “operably linked” refers to the association of nucleic acidsequences on a single nucleic acid fragment so that the function of oneis regulated by the other. For example, a promoter is operably linkedwith a coding sequence when it is capable of regulating the expressionof that coding sequence (i.e., that the coding sequence is under thetranscriptional control of the promoter). Coding sequences can beoperably linked to regulatory sequences in a sense or antisenseorientation. In another example, the complementary RNA regions of theinvention can be operably linked, either directly or indirectly, 5′ tothe target mRNA, or 3′ to the target mRNA, or within the target mRNA, ora first complementary region is 5′ and its complement is 3′ to thetarget mRNA.

The term “expression”, as used herein, refers to the production of afunctional end-product. Expression of a gene involves transcription ofthe gene and translation of the mRNA into a precursor or mature protein.“Antisense inhibition” refers to the production of antisense RNAtranscripts capable of suppressing the expression of the target protein.“Co-suppression” refers to the production of sense RNA transcriptscapable of suppressing the expression of identical or substantiallysimilar foreign or endogenous genes (U.S. Pat. No. 5,231,020).

“Mature” protein refers to a post-translationally processed polypeptide;i.e., one from which any pre- or propeptides present in the primarytranslation product have been removed. “Precursor” protein refers to theprimary product of translation of mRNA; i.e., with pre- and pro-peptidesstill present. Pre- and pro-peptides may be but are not limited tointracellular localization signals.

“Stable transformation” refers to the transfer of a nucleic acidfragment into a genome of a host organism, resulting in geneticallystable inheritance. In contrast, “transient transformation” refers tothe transfer of a nucleic acid fragment into the nucleus, orDNA-containing organelle, of a host organism resulting in geneexpression without integration or stable inheritance. Host organismscontaining the transformed nucleic acid fragments are referred to as“transgenic” organisms. The preferred method of cell transformation ofrice, corn and other monocots is the use of particle-accelerated or“gene gun” transformation technology (Klein et al., (1987) Nature(London) 327:70-73; U.S. Pat. No. 4,945,050), or anAgrobacterium-mediated method using an appropriate Ti plasmid containingthe transgene (Ishida Y. et al., 1996, Nature Biotech. 14:745-750). Theterm “transformation” as used herein refers to both stabletransformation and transient transformation.

Standard recombinant DNA and molecular cloning techniques used hereinare well known in the art and are described more fully in Sambrook, J.,Fritsch, E. F. and Maniatis, T., Molecular Cloning: A Laboratory Manual;Cold Spring Harbor Laboratory Press: Cold Spring Harbor, 1989(hereinafter “Sambrook”).

The term “recombinant” refers to an artificial combination of twootherwise separated segments of sequence, e.g., by chemical synthesis orby the manipulation of isolated segments of nucleic acids by geneticengineering techniques.

“PCR” or “Polymerase Chain Reaction” is a technique for the synthesis oflarge quantities of specific DNA segments, consists of a series ofrepetitive cycles (Perkin Elmer Cetus Instruments, Norwalk, Conn.).Typically, the double stranded DNA is heat denatured, the two primerscomplementary to the 3′ boundaries of the target segment are annealed atlow temperature and then extended at an intermediate temperature. Oneset of these three consecutive steps is referred to as a cycle.

Polymerase chain reaction (“PCR”) is a powerful technique used toamplify DNA millions of fold, by repeated replication of a template, ina short period of time. (Mullis et al., Cold Spring Harbor Symp. Quant.Biol. 51:263-273 (1986); Erlich et al., European Patent Application No.50,424; European Patent Application No. 84,796; European PatentApplication No. 258,017; European Patent Application No. 237,362;Mullis, European Patent Application No. 201,184; Mullis et al., U.S.Pat. No. 4,683,202; Erlich, U.S. Pat. No. 4,582,788; and Saiki et al.,U.S. Pat. No. 4,683,194). The process utilizes sets of specific in vitrosynthesized oligonucleotides to prime DNA synthesis. The design of theprimers is dependent upon the sequences of DNA that are desired to beanalyzed. The technique is carried out through many cycles (usually20-50) of melting the template at high temperature, allowing the primersto anneal to complementary sequences within the template and thenreplicating the template with DNA polymerase.

The products of PCR reactions are analyzed by separation in agarose gelsfollowed by ethidium bromide staining and visualization with UVtransillumination. Alternatively, radioactive dNTPs can be added to thePCR in order to incorporate label into the products. In this case theproducts of PCR are visualized by exposure of the gel to x-ray film. Theadded advantage of radiolabeling PCR products is that the levels ofindividual amplification products can be quantitated.

The terms “recombinant construct”, “expression construct” and“recombinant expression construct” are used interchangeably herein.These terms refer to a functional unit of genetic material that can beinserted into the genome of a cell using standard methodology well knownto one skilled in the art. Such construct may be itself or may be usedin conjunction with a vector. If a vector is used then the choice ofvector is dependent upon the method that will be used to transform hostplants as is well known to those skilled in the art. For example, aplasmid vector can be used. The skilled artisan is well aware of thegenetic elements that must be present on the vector in order tosuccessfully transform, select and propagate host cells comprising anyof the isolated nucleic acid fragments of the invention. The skilledartisan will also recognize that different independent transformationevents will result in different levels and patterns of expression (Joneset al., (1985) EMBO J. 4:2411-2418; De Almeida et al., (1989) Mol. Gen.Genetics 218:78-86), and thus that multiple events must be screened inorder to obtain lines displaying the desired expression level andpattern. Such screening may be accomplished by Southern analysis of DNA,Northern analysis of mRNA expression, Western analysis of proteinexpression, or phenotypic analysis.

Production of the Δ6-Desaturase Enyzme

Once the gene encoding the Δ6-desaturase enzyme has been isolated, itmay then be introduced into either a prokaryotic or eukaryotic host cellthrough the use of a vector or construct. The vector, for example, abacteriophage, cosmid or plasmid, may comprise the nucleotide sequenceencoding the Δ6-desaturase enzyme, as well as any regulatory sequence(e.g., promoter) which is functional in the host cell and is able toelicit expression of the desaturase encoded by the nucleotide sequence.The regulatory sequence (e.g., promoter) is in operable associationwith, or operably linked to, the nucleotide sequence. (A promoter issaid to be “operably linked” with a coding sequence if the promoteraffects transcription or expression of the coding sequence.) Suitablepromoters include, for example, those from genes encoding alcoholdehydrogenase, glyceraldehyde-3-phosphate dehydrogenase,phosphoglucoisomerase, phosphoglycerate kinase, acid phosphatase, T7,TPI, lactase, metallothionein, cytomegalovirus immediate early, wheyacidic protein, glucoamylase, and promoters activated in the presence ofgalactose, for example, GAL1 and GAL10. Additionally, nucleotidesequences which encode other proteins, oligosaccharides, lipids, etc.may also be included within the vector as well as other regulatorysequences such as a polyadenylation signal (e.g., the poly-A signal ofSV-40T-antigen, ovalalbumin or bovine growth hormone). The choice ofsequences present in the construct is dependent upon the desiredexpression products as well as the nature of the host cell. For example,by including a Δ6-desaturase gene sequence of the present invention, anelongase gene sequence and a Δ5-desaturase gene sequence into thevector, one may co-express the encoded Δ6-desaturase, the encodedelongase, as well as the encoded Δ5-desaturase, respectively, in orderto convert, for example, LA to ARA and ALA to EPA.

As noted above, once the vector has been constructed, it may then beintroduced into the host cell of choice by methods known to those ofordinary skill in the art including, for example, transfection,transformation and electroporation (see Molecular Cloning: A LaboratoryManual, 2^(nd) ed., Vol. 1-3, ed. Sambrook et al., Cold Spring HarborLaboratory Press (1989)). The host cell is then cultured under suitableconditions permitting expression of the genes leading to the productionof the desired PUFA, which is then recovered and purified.

Examples of suitable prokaryotic host cells include, for example,bacteria such as Escherichia coli, Bacillus subtilis as well asCyanobacteria such as Spirulina spp. (i.e., blue-green algae). Examplesof suitable eukaryotic host cells include, for example, mammalian cells,plant cells, yeast cells such as Saccharomyces cerevisiae, Saccharomycescarlsbergensis, Lipomyces starkey, Candida spp. such as Yarrowia(Candida) lipolytica, Kluyveromyces spp., Pichia spp., Trichoderma spp.or Hansenula spp., or fungal cells such as filamentous fungal cells, forexample, Aspergillus, Neurospora and Penicillium. Preferably,Saccharomyces cerevisiae (baker's yeast) cells are utilized.

Expression in a host cell can be accomplished in a transient or stablefashion. Transient expression can occur from introduced constructs whichcontain expression signals functional in the host cell, but whichconstructs do not replicate and rarely integrate in the host cell, orwhen the host cell is not proliferating. Transient expression also canbe accomplished by inducing the activity of a regulatable promoteroperably linked to the gene of interest, although such inducible systemsfrequently exhibit a low basal level of expression. Stable expressioncan be achieved by introduction of a construct that can integrate intothe host genome or that autonomously replicates in the host cell. Stableexpression of the gene of interest can be selected through the use of aselectable marker located on or transfected with the expressionconstruct, followed by selection for cells expressing the marker. Whenstable expression results from integration, the site of the construct'sintegration can occur randomly within the host genome or can be targetedthrough the use of constructs containing regions of homology with thehost genome sufficient to target recombination with the host locus.Where constructs are targeted to an endogenous locus, all or some of thetranscriptional and translational regulatory regions can be provided bythe endogenous locus.

A transgenic mammal may also be used in order to express the enzyme ofinterest (i.e., Δ6-desaturase), and ultimately the PUFA(s) of interest.More specifically, once the above-described construct is created, it maybe inserted into the pronucleus of an embryo. The embryo may then beimplanted into a recipient female. Alternatively, a nuclear transfermethod could also be utilized (Schnieke et al., Science 278:2130-2133(1997)). Gestation and birth are then permitted (see, e.g., U.S. Pat.No. 5,750,176 and U.S. Pat. No. 5,700,671). Milk, tissue or other fluidsamples from the offspring should then contain altered levels of PUFAs,as compared to the levels normally found in the non-transgenic animal.Subsequent generations may be monitored for production of the altered orenhanced levels of PUFAs and thus incorporation of the gene encoding thedesired desaturase enzyme into their genomes. The mammal utilized as thehost may be selected from the group consisting of, for example, a mouse,a rat, a rabbit, a pig, a goat, a sheep, a horse and a cow. However, anymammal may be used provided it has the ability to incorporate DNAencoding the enzyme of interest into its genome.

For expression of a desaturase polypeptide, functional transcriptionaland translational initiation and termination regions are operably linkedto the DNA encoding the desaturase polypeptide. Transcriptional andtranslational initiation and termination regions are derived from avariety of nonexclusive sources, including the DNA to be expressed,genes known or suspected to be capable of expression in the desiredsystem, expression vectors, chemical synthesis, or from an endogenouslocus in a host cell. Expression in a plant tissue and/or plant partpresents certain efficiencies, particularly where the tissue or part isone which is harvested early, such as seed, leaves, fruits, flowers,roots, etc. Expression can be targeted to that location with the plantby utilizing specific regulatory sequence such as those of U.S. Pat.Nos. 5,463,174, 4,943,674, 5,106,739, 5,175,095, 5,420,034, 5,188,958,and 5,589,379. Alternatively, the expressed protein can be an enzymewhich produces a product which may be incorporated, either directly orupon further modifications, into a fluid fraction from the host plant.Expression of a desaturase gene, or antisense desaturase transcripts,can alter the levels of specific PUFAs, or derivatives thereof, found inplant parts and/or plant tissues. The desaturase polypeptide codingregion may be expressed either by itself or with other genes, in orderto produce tissues and/or plant parts containing higher proportions ofdesired PUFAs or in which the PUFA composition more closely resemblesthat of human breast milk (Prieto et al., PCT publication WO 95/24494).The termination region may be derived from the 3′ region of the genefrom which the initiation region was obtained or from a different gene.A large number of termination regions are known to and have been foundto be satisfactory in a variety of hosts from the same and differentgenera and species. The termination region usually is selected as amatter of convenience rather than because of any particular property.

As noted above, a plant (e.g., Glycine max (soybean), cotton, safflower,sunflower, palm, coconut, maize, nuts, beans, peas or Brassica napus(canola)) or plant tissue may also be utilized as a host or host cell,respectively, for expression of the desaturase enzyme which may, inturn, be utilized in the production of polyunsaturated fatty acids. Morespecifically, desired PUFAS can be expressed in seed. Methods ofisolating seed oils are known in the art. Thus, in addition to providinga source for PUFAs, seed oil components may be manipulated through theexpression of the desaturase gene, as well as perhaps other desaturasegenes and elongase genes, in order to provide seed oils that can beadded to nutritional compositions, pharmaceutical compositions, animalfeeds and cosmetics. Once again, a vector which comprises a DNA sequenceencoding the desaturase operably linked to a promoter, will beintroduced into the plant tissue or plant for a time and underconditions sufficient for expression of the desaturase gene. The vectormay also comprise one or more genes that encode other enzymes, forexample, Δ5-desaturase, elongase, Δ12-desaturase, Δ15-desaturase,Δ17-desaturase, and/or Δ19-desaturase. The plant tissue or plant mayproduce the relevant substrate (e.g., linoleic acid or α-linolenic acid)upon which the enzyme acts or a vector encoding enzymes which producesuch substrates may be introduced into the plant tissue, plant cell orplant. In addition, substrate may be sprayed on plant tissues expressingthe appropriate enzymes. Using these various techniques, one may producePUFAs (e.g., n-6 unsaturated fatty acids such as ω6-docosapentaenoicacid, or n-3 fatty acids such as docosahexaenoic acid) by use of a plantcell, plant tissue or plant. It should also be noted that the inventionalso encompasses a transgenic plant comprising the above-describedvector, wherein expression of the nucleotide sequence of the vectorresults in production of a polyunsaturated fatty acid in, for example,the seeds of the transgenic plant.

The regeneration, development, and cultivation of plants from singleplant protoplast transformants or from various transformed explants iswell known in the art (Weissbach and Weissbach, In: Methods for PlantMolecular Biology, (Eds.), Academic Press, Inc. San Diego, Calif.,(1988)). This regeneration and growth process typically includes thesteps of selection of transformed cells, culturing those individualizedcells through the usual stages of embryonic development through therooted plantlet stage. Transgenic embryos and seeds are similarlyregenerated. The resulting transgenic rooted shoots are thereafterplanted in an appropriate plant growth medium such as soil.

The development or regeneration of plants containing the foreign,exogenous gene that encodes a protein of interest is well known in theart. Preferably, the regenerated plants are self-pollinated to providehomozygous transgenic plants. Otherwise, pollen obtained from theregenerated plants is crossed to seed-grown plants of agronomicallyimportant lines. Conversely, pollen from plants of these important linesis used to pollinate regenerated plants. A transgenic plant of thepresent invention containing a desired polypeptide is cultivated usingmethods well known to one skilled in the art.

There are a variety of methods for the regeneration of plants from planttissue. The particular method of regeneration will depend on thestarting plant tissue and the particular plant species to beregenerated.

Methods for transforming dicots, primarily by use of Agrobacteriumtumefaciens, and obtaining transgenic plants have been published forcotton (U.S. Pat. No. 5,004,863, U.S. Pat. No. 5,159,135, U.S. Pat. No.5,518,908); soybean (U.S. Pat. No. 5,569,834, U.S. Pat. No. 5,416,011,McCabe et. al., BiolTechnology 6:923 (1988), Christou et al., PlantPhysiol. 87:671-674 (1988)); Brassica (U.S. Pat. No. 5,463,174); peanut(Cheng et al., Plant Cell Rep. 15:653-657 (1996), McKently et al., PlantCell Rep. 14:699-703 (1995)); papaya; and pea (Grant et al., Plant CellRep. 15:254-258, (1995)).

Transformation of monocotyledons using electroporation, particlebombardment, and Agrobacterium have also been reported. Transformationand plant regeneration have been achieved in asparagus (Bytebier et al.,Proc. Natl. Acad. Sci. (USA) 84:5354, (1987)); barley (Wan and Lemaux,Plant Physiol 104:37 (1994)); Zea mays (Rhodes et al., Science 240:204(1988), Gordon-Kamm et al., Plant Cell 2:603-618 (1990), Fromm et al.,BiolTechnology 8:833 (1990), Koziel et al., BiolTechnology 11:194,(1993), Armstrong et al., Crop Science 35:550-557 (1995)); oat (Somerset al., BiolTechnology 10:1589 (1992)); orchard grass (Horn et al.,Plant Cell Rep. 7:469 (1988)); rice (Toriyama et al., Theor. Appl.Genet. 205:34 (1986); Part et al., Plant Mol. Biol. 32:1135-1148,(1996); Abedinia et al., Aust. J. Plant Physiol. 24:133-141 (1997);Zhang and Wu, Theor. Appl. Genet. 76:835 (1988); Zhang et al. Plant CellRep. 7:379, (1988); Battraw and Hall, Plant Sci. 86:191-202 (1992);Christou et al., Bio/Technology 9:957 (1991)); rye (De la Pena et al.,Nature 325:274 (1987)); sugarcane (Bower and Birch, Plant J. 2:409(1992)); tall fescue (Wang et al., Biol. Technology 10:691 (1992)), andwheat (Vasil et al., Biol. Technology 10:667 (1992); U.S. Pat. No.5,631,152).

Assays for gene expression based on the transient expression of clonednucleic acid constructs have been developed by introducing the nucleicacid molecules into plant cells by polyethylene glycol treatment,electroporation, or particle bombardment (Marcotte et al., Nature335:454-457 (1988); Marcotte et al., Plant Cell 1:523-532 (1989);McCarty et al., Cell 66:895-905 (1991); Hattori et al., Genes Dev.6:609-618 (1992); Goff et al., EMBO J. 9:2517-2522 (1990)).

Transient expression systems may be used to functionally dissect geneconstructs (see generally, Maliga et al., Methods in Plant MolecularBiology, Cold Spring Harbor Press (1995)). It is understood that any ofthe nucleic acid molecules of the present invention can be introducedinto a plant cell in a permanent or transient manner in combination withother genetic elements such as vectors, promoters, enhancers etc.

In addition to the above discussed procedures, practitioners arefamiliar with the standard resource materials which describe specificconditions and procedures for the construction, manipulation andisolation of macromolecules (e.g., DNA molecules, plasmids, etc.),generation of recombinant organisms and the screening and isolating ofclones, (see for example, Sambrook et al., Molecular Cloning: ALaboratory Manual, Cold Spring Harbor Press (1989); Maliga et al.,Methods in Plant Molecular Biology, Cold Spring Harbor Press (1995);Birren et al., Genome Analysis: Detecting Genes, 1, Cold Spring Harbor,N.Y. (1998); Birren et al., Genome Analysis: Analyzing DNA, 2, ColdSpring Harbor, N.Y. (1998); Plant Molecular Biology: A LaboratoryManual, eds. Clark, Springer, New York (1997)).

The substrates which may be produced by the host cell either naturallyor transgenically, as well as the enzymes which may be encoded by DNAsequences present in the vector, which is subsequently introduced intothe host cell, are shown in FIG. 1.

Uses of the Δ6-Desaturase Gene and Enzyme Encoded Thereby

As noted above, the isolated desaturase genes and the desaturase enzymesencoded thereby have many uses. For example, the gene and correspondingenzyme may be used indirectly or directly in the production ofpolyunsaturated fatty acids, for example, Δ6-desaturase may be used inthe production of γ-linolenic acid or stearidonic acid. “Directly” ismeant to encompass the situation where the enzyme directly converts theacid to another acid, the latter of which is utilized in a composition(e.g., the conversion of linoleic acid to γ-linolenic acid).“Indirectly” is meant to encompass the situation where an acid (e.g.,α-linolenic acid) is converted to another acid (i.e., a pathwayintermediate such as stearidonic acid) by the desaturase, and then thelatter acid is converted to another acid by use of a desaturase ornon-desaturase enzyme (e.g., stearidonic acid to eicosatetraenoic acidby an elongase). Also, the present invention includes “indirect”situations in which the PUFA is first converted to anotherpolyunsaturated fatty acid by a non-Δ6-desaturase enzyme (for example,an elongase or another desaturase) and then converted to a final productvia Δ6-desaturase. For example, linoleic acid may be converted toα-linolenic acid by a desaturase (i.e., Δ15-desaturase), and thenconverted to stearidonic acid by a Δ6-desaturase. These polyunsaturatedfatty acids (i.e., those produced either directly or indirectly byactivity of the Δ6-desaturase enzyme) may be added to, for example,nutritional compositions, pharmaceutical compositions, cosmetics, andanimal feeds, all of which are encompassed by the present invention.These uses are described, in detail, below.

Nutritional Compositions

The present invention includes nutritional compositions. Suchcompositions, for purposes of the present invention, include any food orpreparation for human consumption including for enteral or parenteralconsumption, which when taken into the body (a) serve to nourish orbuild up tissues or supply energy and/or (b) maintain, restore orsupport adequate nutritional status or metabolic function.

The nutritional composition of the present invention comprises at leastone oil or acid produced directly or indirectly by use of the desaturasegene, in accordance with the present invention, and may either be in asolid or liquid form. Additionally, the composition may include ediblemacronutrients, vitamins and minerals in amounts desired for aparticular use. The amount of such ingredients will vary depending onwhether the composition is intended for use with normal, healthyinfants, children or adults having specialized needs such as those whichaccompany certain metabolic conditions (e.g., metabolic disorders).

Examples of macronutrients which may be added to the composition includebut are not limited to edible fats, carbohydrates and proteins. Examplesof such edible fats include but are not limited to coconut oil, borageoil, fungal oil, black current oil, soy oil, and mono- and diglycerides.Examples of such carbohydrates include but are not limited to glucose,edible lactose and hydrolyzed starch. Additionally, examples of proteinswhich may be utilized in the nutritional composition of the inventioninclude but are not limited to soy proteins, electrodialysed whey,electrodialysed skim milk, milk whey, or the hydrolysates of theseproteins.

With respect to vitamins and minerals, the following may be added to thenutritional compositions of the present invention: calcium, phosphorus,potassium, sodium, chloride, magnesium, manganese, iron, copper, zinc,selenium, iodine, and Vitamins A, E, D, C, and the B complex. Other suchvitamins and minerals may also be added.

The components utilized in the nutritional compositions of the presentinvention will be of semi-purified or purified origin. By semi-purifiedor purified is meant a material which has been prepared by purificationof a natural material or by synthesis.

Examples of nutritional compositions of the present invention includebut are not limited to infant formulas, dietary supplements (e.g., adultnutritional products and oil), dietary substitutes, and rehydrationcompositions. Nutritional compositions of particular interest includebut are not limited to those utilized for enteral and parenteralsupplementation for infants, specialized infant formulas, supplementsfor the elderly, and supplements for those with gastrointestinaldifficulties and/or malabsorption.

The nutritional composition of the present invention may also be addedto food even when supplementation of the diet is not required. Forexample, the composition may be added to food of any type including butnot limited to margarines, modified butters, cheeses, milk, yogurt,chocolate, candy, snacks, salad oils, cooking oils, cooking fats, meats,fish and beverages.

In a preferred embodiment of the present invention, the nutritionalcomposition is an enteral nutritional product, more preferably, an adultor pediatric enteral nutritional product. This composition may beadministered to adults or children experiencing stress or havingspecialized needs due to chronic or acute disease states. Thecomposition may comprise, in addition to polyunsaturated fatty acidsproduced in accordance with the present invention, macronutrients,vitamins and minerals as described above. The macronutrients may bepresent in amounts equivalent to those present in human milk or on anenergy basis, i.e., on a per calorie basis.

Methods for formulating liquid or solid enteral and parenteralnutritional formulas are well known in the art. (See also the Examplesbelow.)

The enteral formula, for example, may be sterilized and subsequentlyutilized on a ready-to-feed (RTF) basis or stored in a concentratedliquid or powder. The powder can be prepared by spray drying the formulaprepared as indicated above, and reconstituting it by rehydrating theconcentrate. Adult and pediatric nutritional formulas are well known inthe art and are commercially available (e.g., Similac®, Ensure®, Jevity®and Alimentum® from Ross Products Division, Abbott Laboratories,Columbus, Ohio). An oil or acid produced in accordance with the presentinvention may be added to any of these formulas.

The energy density of the nutritional compositions of the presentinvention, when in liquid form, may range from about 0.6 Kcal to about 3Kcal per ml. When in solid or powdered form, the nutritional supplementsmay contain from about 1.2 to more than 9 Kcals per gram, preferablyabout 3 to 7 Kcals per gm. In general, the osmolality of a liquidproduct should be less than 700 mOsm and, more preferably, less than 660mOsm.

The nutritional formula may include macronutrients, vitamins, andminerals, as noted above, in addition to the PUFAs produced inaccordance with the present invention. The presence of these additionalcomponents helps the individual ingest the minimum daily requirements ofthese elements. In addition to the provision of PUFAs, it may also bedesirable to add zinc, copper, folic acid and antioxidants to thecomposition. It is believed that these substances boost a stressedimmune system and will therefore provide further benefits to theindividual receiving the composition. A pharmaceutical composition mayalso be supplemented with these elements.

In a more preferred embodiment, the nutritional composition comprises,in addition to antioxidants and at least one PUFA, a source ofcarbohydrate wherein at least 5 weight percent of the carbohydrate isindigestible oligosaccharide. In a more preferred embodiment, thenutritional composition additionally comprises protein, taurine, andcarnitine.

As noted above, the PUFAs produced in accordance with the presentinvention, or derivatives thereof, may be added to a dietary substituteor supplement, particularly an infant formula, for patients undergoingintravenous feeding or for preventing or treating malnutrition or otherconditions or disease states. As background, it should be noted thathuman breast milk has a fatty acid profile comprising from about 0.15%to about 0.36% as DHA, from about 0.03% to about 0.13% as EPA, fromabout 0.30% to about 0.88% as AA, from about 0.22% to about 0.67% asDGLA, and from about 0.27% to about 1.04% as GLA. Thus, fatty acids suchas AA, EPA and/or docosahexaenoic acid (DHA), produced in accordancewith the present invention, can be used to alter, for example, thecomposition of infant formulas in order to better replicate the PUFAcontent of human breast milk or to alter the presence of PUFAs normallyfound in a non-human mammal's milk. In particular, a composition for usein a pharmacologic or food supplement, particularly a breast milksubstitute or supplement, will preferably comprise one or more of AA,DGLA and GLA. More preferably, the oil will comprise from about 0.3 to30% AA, from about 0.2 to 30% DGLA, and/or from about 0.2 to about 30%GLA.

Parenteral nutritional compositions comprising from about 2 to about 30weight percent fatty acids calculated as triglycerides are encompassedby the present invention. The preferred composition has about 1 to about25 weight percent of the total PUFA composition as GLA (U.S. Pat. No.5,196,198). Other vitamins, particularly fat-soluble vitamins such asvitamin A, D, E and L-carnitine can optionally be included. Whendesired, a preservative such as alpha-tocopherol may be added in anamount of about 0.1% by weight.

In addition, the ratios of AA, DGLA and GLA can be adapted for aparticular given end use. When formulated as a breast milk supplement orsubstitute, a composition which comprises one or more of AA, DGLA andGLA will be provided in a ratio of about 1:19:30 to about 6:1:0.2,respectively. For example, the breast milk of animals can vary in ratiosof AA:DGLA:GLA ranging from 1:19:30 to 6:1:0.2, which includesintermediate ratios which are preferably about 1:1:1, 1:2:1, 1:1:4. Whenproduced together in a host cell, adjusting the rate and percent ofconversion of a precursor substrate such as GLA and DGLA to AA can beused to precisely control the PUFA ratios. For example, a 5% to 10%conversion rate of DGLA to AA can be used to produce an AA to DGLA ratioof about 1:19, whereas a conversion rate of about 75% TO 80% can be usedto produce an AA to DGLA ratio of about 6:1. Therefore, whether in acell culture system or in a host animal, regulating the timing, extentand specificity of desaturase expression, as well as the expression ofother desaturases and elongases, can be used to modulate PUFA levels andratios. The PUFAs produced in accordance with the present invention(e.g., AA and EPA) may then be combined with other PUFAs/acids (e.g.,GLA) in the desired concentrations and ratios.

Additionally, PUFA produced in accordance with the present invention orhost cells containing them may also be used as animal food supplementsto alter an animal's tissue or milk fatty acid composition to one moredesirable for human or animal consumption.

Pharmaceutical Compositions

The present invention also encompasses a pharmaceutical compositioncomprising one or more of the acids and/or resulting oils produced usingthe desaturase genes, in accordance with the methods described herein.More specifically, such a pharmaceutical composition may comprise one ormore of the acids and/or oils as well as a standard, well-known,non-toxic pharmaceutically acceptable carrier, adjuvant or vehicle suchas, for example, phosphate buffered saline, water, ethanol, polyols,vegetable oils, a wetting agent or an emulsion such as a water/oilemulsion. The composition may be in either a liquid or solid form. Forexample, the composition may be in the form of a tablet, capsule,ingestible liquid or powder, injectible, or topical ointment or cream.Proper fluidity can be maintained, for example, by the maintenance ofthe required particle size in the case of dispersions and by the use ofsurfactants. It may also be desirable to include isotonic agents, forexample, sugars, sodium chloride and the like. Besides such inertdiluents, the composition can also include adjuvants, such as wettingagents, emulsifying and suspending agents, sweetening agents, flavoringagents and perfuming agents.

Suspensions, in addition to the active compounds, may comprisesuspending agents such as, for example, ethoxylated isostearyl alcohols,polyoxyethylene sorbitol and sorbitan esters, microcrystallinecellulose, aluminum metahydroxide, bentonite, agar-agar and tragacanthor mixtures of these substances.

Solid dosage forms such as tablets and capsules can be prepared usingtechniques well known in the art. For example, PUFAs produced inaccordance with the present invention can be tableted with conventionaltablet bases such as lactose, sucrose, and cornstarch in combinationwith binders such as acacia, cornstarch or gelatin, disintegratingagents such as potato starch or alginic acid, and a lubricant such asstearic acid or magnesium stearate. Capsules can be prepared byincorporating these excipients into a gelatin capsule along withantioxidants and the relevant PUFA(s). The antioxidant and PUFAcomponents should fit within the guidelines presented above.

For intravenous administration, the PUFAs produced in accordance withthe present invention or derivatives thereof may be incorporated intocommercial formulations such as Intralipids™. The typical normal adultplasma fatty acid profile comprises 6.64 to 9.46% of AA, 1.45 to 3.11%of DGLA, and 0.02 to 0.08% of GLA. These PUFAs or their metabolicprecursors can be administered alone or in combination with other PUFAsin order to achieve a normal fatty acid profile in a patient. Wheredesired, the individual components of the formulations may be providedindividually, in kit form, for single or multiple use. A typical dosageof a particular fatty acid is from 0.1 mg to 20 g (up to 100 g) dailyand is preferably from 10 mg to 1, 2, 5 or 10 g daily.

Possible routes of administration of the pharmaceutical compositions ofthe present invention include, for example, enteral (e.g., oral andrectal) and parenteral. For example, a liquid preparation may beadministered, for example, orally or rectally. Additionally, ahomogenous mixture can be completely dispersed in water, admixed understerile conditions with physiologically acceptable diluents,preservatives, buffers or propellants in order to form a spray orinhalant.

The route of administration will, of course, depend upon the desiredeffect. For example, if the composition is being utilized to treatrough, dry, or aging skin, to treat injured or burned skin, or to treatskin or hair affected by a disease or condition, it may perhaps beapplied topically.

The dosage of the composition to be administered to the patient may bedetermined by one of ordinary skill in the art and depends upon variousfactors such as weight of the patient, age of the patient, immune statusof the patient, etc.

With respect to form, the composition may be, for example, a solution, adispersion, a suspension, an emulsion or a sterile powder which is thenreconstituted.

The present invention also includes the treatment of various disordersby use of the pharmaceutical and/or nutritional compositions describedherein. In particular, the compositions of the present invention may beused to treat restenosis after angioplasty. Furthermore, symptoms ofinflammation, rheumatoid arthritis, asthma and psoriasis may also betreated with the compositions of the invention. Evidence also indicatesthat PUFAs may be involved in calcium metabolism; thus, the compositionsof the present invention may, perhaps, be utilized in the treatment orprevention of osteoporosis and of kidney or urinary tract stones.

Additionally, the compositions of the present invention may also be usedin the treatment of cancer. Malignant cells have been shown to havealtered fatty acid compositions. Addition of fatty acids has been shownto slow their growth, cause cell death and increase their susceptibilityto chemotherapeutic agents. Moreover, the compositions of the presentinvention may also be useful for treating cachexia associated withcancer.

The compositions of the present invention may also be used to treatdiabetes (see U.S. Pat. No. 4,826,877 and Horrobin et al., Am. J. Clin.Nutr. Vol. 57 (Suppl.) 732S-737S). Altered fatty acid metabolism andcomposition have been demonstrated in diabetic animals.

Furthermore, the compositions of the present invention, comprising PUFAsproduced either directly or indirectly through the use of the desaturaseenzymes, may also be used in the treatment of eczema, in the reductionof blood pressure, and in the improvement of mathematics examinationscores. Additionally, the compositions of the present invention may beused in inhibition of platelet aggregation, induction of vasodilation,reduction in cholesterol levels, inhibition of proliferation of vesselwall smooth muscle and fibrous tissue (Brenner et al., Adv. Exp. Med.Biol. Vol. 83, p. 85-101, 1976), reduction or prevention ofgastrointestinal bleeding and other side effects of non-steroidalanti-inflammatory drugs (see U.S. Pat. No. 4,666,701), prevention ortreatment of endometriosis and premenstrual syndrome (see U.S. Pat. No.4,758,592), and treatment of myalgic encephalomyelitis and chronicfatigue after viral infections (see U.S. Pat. No. 5,116,871).

Further uses of the compositions of the present invention include use inthe treatment of AIDS, multiple sclerosis, and inflammatory skindisorders, as well as for maintenance of general health.

Additionally, the composition of the present invention may be utilizedfor cosmetic purposes. It may be added to pre-existing cosmeticcompositions such that a mixture is formed or may be used as a solecomposition.

Veterinary Applications

It should be noted that the above-described pharmaceutical andnutritional compositions may be utilized in connection with animals(i.e., domestic or non-domestic), as well as humans, as animalsexperience many of the same needs and conditions as humans. For example,the oil or acids of the present invention may be utilized in animal feedsupplements, animal feed substitutes, animal vitamins or in animaltopical ointments.

Nutritional Compositions

The PUFAs described in the Detailed Description may be utilized invarious nutritional supplements, infant formulations, nutritionalsubstitutes and other nutritional solutions.

I. Infant Formulations

A. Isomil® Soy Formula with Iron:

Usage: As a beverage for infants, children and adults with an allergy orsensitivity to cows milk. A feeding for patients with disorders forwhich lactose should be avoided: lactase deficiency, lactose intoleranceand galactosemia.

Features:

-   -   Soy protein isolate to avoid symptoms of cow's-milk-protein        allergy or sensitivity.    -   Lactose-free formulation to avoid lactose-associated diarrhea.    -   Low osmolality (240 mOs/kg water) to reduce risk of osmotic        diarrhea.    -   Dual carbohydrates (corn syrup and sucrose) designed to enhance        carbohydrate absorption and reduce the risk of exceeding the        absorptive capacity of the damaged gut.    -   1.8 mg of Iron (as ferrous sulfate) per 100 Calories to help        prevent iron deficiency.    -   Recommended levels of vitamins and minerals.    -   Vegetable oils to provide recommended levels of essential fatty        acids.    -   Milk-white color, milk-like consistency and pleasant aroma.

Ingredients: (Pareve) 85% water, 4.9% corn syrup, 2.6% sugar (sucrose),2.1% soy oil, 1.9% soy protein isolate, 1.4% coconut oil, 0.15% calciumcitrate, 0.11% calcium phosphate tribasic, potassium citrate, potassiumphosphate monobasic, potassium chloride, mono- and disglycerides, soylecithin, carrageenan, ascorbic acid, L-methionine, magnesium chloride,potassium phosphate dibasic, sodium chloride, choline chloride, taurine,ferrous sulfate, m-inositol, alpha-tocopheryl acetate, zinc sulfate,L-carnitine, niacinamide, calcium pantothenate, cupric sulfate, vitaminA palmitate, thiamine chloride hydrochloride, riboflavin, pyridoxinehydrochloride, folic acid, manganese sulfate, potassium iodide,phylloquinone, biotin, sodium selenite, vitamin D3 and cyanocobalamin.

B. Isomil® DF Soy Formula for Diarrhea:

Usage: As a short-term feeding for the dietary management of diarrhea ininfants and toddlers.

Features:

-   -   First infant formula to contain added dietary fiber from soy        fiber specifically for diarrhea management.    -   Clinically shown to reduce the duration of loose, watery stools        during mild to severe diarrhea in infants.    -   Nutritionally complete to meet the nutritional needs of the        infant.    -   Soy protein isolate with added L-methionine meets or exceeds an        infant's requirement for all essential amino acids.    -   Lactose-free formulation to avoid lactose-associated diarrhea.    -   Low osmolality (240 mOsm/kg water) to reduce the risk of osmotic        diarrhea.    -   Dual carbohydrates (corn syrup and sucrose) designed to enhance        carbohydrate absorption and reduce the risk of exceeding the        absorptive capacity of the damaged gut.    -   Meets or exceeds the vitamin and mineral levels recommended by        the Committee on Nutrition of the American Academy of Pediatrics        and required by the Infant Formula Act.    -   1.8 mg of iron (as ferrous sulfate) per 100 Calories to help        prevent iron deficiency.    -   Vegetable oils to provide recommended levels of essential fatty        acids.

Ingredients: (Pareve) 86% water, 4.8% corn syrup, 2.5% sugar (sucrose),2.1% soy oil, 2.0% soy protein isolate, 1.4% coconut oil, 0.77% soyfiber, 0.12% calcium citrate, 0.11% calcium phosphate tribasic, 0.10%potassium citrate, potassium chloride, potassium phosphate monobasic,mono and diglycerides, soy lecithin, carrageenan, magnesium chloride,ascorbic acid, L-methionine, potassium phosphate dibasic, sodiumchloride, choline chloride, taurine, ferrous sulfate, m-inositol,alpha-tocopheryl acetate, zinc sulfate, L-carnitine, niacinamide,calcium pantothenate, cupric sulfate, vitamin A palmitate, thiaminechloride hydrochloride, riboflavin, pyridoxine hydrochloride, folicacid, manganese sulfate, potassium iodide, phylloquinone, biotin, sodiumselenite, vitamin D3 and cyanocobalamin.

C. Isomil® SF Sucrose-Free Soy Formula with Iron:

Usage: As a beverage for infants, children and adults with an allergy orsensitivity to cow's-milk protein or an intolerance to sucrose. Afeeding for patients with disorders for which lactose and sucrose shouldbe avoided.

Features:

-   -   Soy protein isolate to avoid symptoms of cow's-milk-protein        allergy or sensitivity.    -   Lactose-free formulation to avoid lactose-associated diarrhea        (carbohydrate source is Polycose® Glucose Polymers).    -   Sucrose free for the patient who cannot tolerate sucrose.    -   Low osmolality (180 mOsm/kg water) to reduce risk of osmotic        diarrhea.    -   1.8 mg of iron (as ferrous sulfate) per 100 Calories to help        prevent iron deficiency.    -   Recommended levels of vitamins and minerals.    -   Vegetable oils to provide recommended levels of essential fatty        acids.    -   Milk-white color, milk-like consistency and pleasant aroma.

Ingredients: (Pareve) 75% water, 11.8% hydrolized cornstarch, 4.1% soyoil, 4.1% soy protein isolate, 2.8% coconut oil, 1.0% modifiedcornstarch, 0.38% calcium phosphate tribasic, 0.17% potassium citrate,0.13% potassium chloride, mono- and diglycerides, soy lecithin,magnesium chloride, abscorbic acid, L-methionine, calcium carbonate,sodium chloride, choline chloride, carrageenan, taurine, ferroussulfate, m-inositol, alpha-tocopheryl acetate, zinc sulfate,L-carnitine, niacinamide, calcium pantothenate, cupric sulfate, vitaminA palmitate, thiamine chloride hydrochloride, riboflavin, pyridoxinehydrochloride, folic acid, manganese sulfate, potassium iodide,phylloquinone, biotin, sodium selenite, vitamin D3 and cyanocobalamin.

D. Isomil® 20 Soy Formula with Iron Ready to Feed, 20 Cal/fl oz.:

Usage: When a soy feeding is desired.

Ingredients: (Pareve) 85% water, 4.9% corn syrup, 2.6% sugar (sucrose),2.1% soy oil, 1.9% soy protein isolate, 1.4% coconut oil, 0.15% calciumcitrate, 0. 11% calcium phosphate tribasic, potassium citrate, potassiumphosphate monobasic, potassium chloride, mono- and diglycerides, soylecithin, carrageenan, abscorbic acid, L-methionine, magnesium chloride,potassium phosphate dibasic, sodium chloride, choline chloride, taurine,ferrous sulfate, m-inositol, alpha-tocopheryl acetate, zinc sulfate,L-carnitine, niacinamide, calcium pantothenate, cupric sulfate, vitaminA palmitate, thiamine chloride hydrochloride, riboflavin, pyridoxinehydrochloride, folic acid, manganese sulfate, potassium iodide,phylloquinone, biotin, sodium selenite, vitamin D3 and cyanocobalamin.

E. Similac® Infant Formula:

Usage: When an infant formula is needed: if the decision is made todiscontinue breastfeeding before age 1 year, if a supplement tobreastfeeding is needed or as a routine feeding if breastfeeding is notadopted.

Features:

-   -   Protein of appropriate quality and quantity for good growth;        heat-denatured, which reduces the risk of milk-associated        enteric blood loss.    -   Fat from a blend of vegetable oils (doubly homogenized),        providing essential linoleic acid that is easily absorbed.    -   Carbohydrate as lactose in proportion similar to that of human        milk.    -   Low renal solute load to minimize stress on developing organs.    -   Powder, Concentrated Liquid and Ready To Feed forms.

Ingredients: (-D) Water, nonfat milk, lactose, soy oil, coconut oil,mono- and diglycerides, soy lecithin, abscorbic acid, carrageenan,choline chloride, taurine, m-inositol, alpha-tocopheryl acetate, zincsulfate, niacinamide, ferrous sulfate, calcium pantothenate, cupricsulfate, vitamin A palmitate, thiamine chloride hydrochloride,riboflavin, pyridoxine hydrochloride, folic acid, manganese sulfate,phylloquinone, biotin, sodium selenite, vitamin D3 and cyanocobalamin.

F. Similac® NeoCare Premature Infant Formula with Iron:

Usage: For premature infants' special nutritional needs after hospitaldischarge. Similac NeoCare is a nutritionally complete formula developedto provide premature infants with extra calories, protein, vitamins andminerals needed to promote catch-up growth and support development.

Features:

-   -   Reduces the need for caloric and vitamin supplementation. More        calories (22 Cal/fl oz) than standard term formulas (20 Cal/fl        oz).    -   Highly absorbed fat blend, with medium-chain triglycerides        (MCToil) to help meet the special digestive needs of premature        infants.    -   Higher levels of protein, vitamins and minerals per 100 calories        to extend the nutritional support initiated in-hospital.    -   More calcium and phosphorus for improved bone mineralization.

Ingredients: -D Corn syrup solids, nonfat milk, lactose, whey proteinconcentrate, soy oil, high-oleic safflower oil, fractionated coconut oil(medium chain triglycerides), coconut oil, potassium citrate, calciumphosphate tribasic, calcium carbonate, ascorbic acid, magnesiumchloride, potassium chloride, sodium chloride, taurine, ferrous sulfate,m-inositol, choline chloride, ascorbyl palmitate, L-carnitine,alpha-tocopheryl acetate, zinc sulfate, niacinamide, mixed tocopherols,sodium citrate, calcium pantothenate, cupric sulfate, thiamine chloridehydrochloride, vitamin A palmitate, beta carotene, riboflavin,pyridoxine hydrochloride, folic acid, manganese sulfate, phylloquinone,biotin, sodium selenite, vitamin D3 and cyanocobalamin.

G. Similac Natural Care Low-Iron Human Milk

Fortifier Ready To Use, 24 Cal/fl oz.:

Usage: Designed to be mixed with human milk or to be fed alternativelywith human milk to low-birth-weight infants.

Ingredients: -D Water, nonfat milk, hydrolyzed cornstarch, lactose,fractionated coconut oil (medium-chain triglycerides), whey proteinconcentrate, soy oil, coconut oil, calcium phosphate tribasic, potassiumcitrate, magnesium chloride, sodium citrate, ascorbic acid, calciumcarbonate, mono and diglycerides, soy lecithin, carrageenan, cholinechloride, m-inositol, taurine, niacinamide, L-carnitine, alphatocopheryl acetate, zinc sulfate, potassium chloride, calciumpantothenate, ferrous sulfate, cupric sulfate, riboflavin, vitamin Apalmitate, thiamine chloride hydrochloride, pyridoxine hydrochloride,biotin, folic acid, manganese sulfate, phylloquinone, vitamin D3, sodiumselenite and cyanocobalamin.

Various PUFAs of this invention can be substituted and/or added to theinfant formulae described above and to other infant formulae known tothose in the art.

II. Nutritional Formulations

A. ENSURE®

Usage: ENSURE is a low-residue liquid food designed primarily as an oralnutritional supplement to be used with or between meals or, inappropriate amounts, as a meal replacement. ENSURE is lactose- andgluten-free, and is suitable for use in modified diets, includinglow-cholesterol diets. Although it is primarily an oral supplement, itcan be fed by tube.

Patient Conditions:

-   -   For patients on modified diets    -   For elderly patients at nutrition risk    -   For patients with involuntary weight loss    -   For patients recovering from illness or surgery    -   For patients who need a low-residue diet

Ingredients: -D Water, Sugar (Sucrose), Maltodextrin (Corn), Calcium andSodium Caseinates, High-Oleic Safflower Oil, Soy Protein Isolate, SoyOil, Canola Oil, Potassium Citrate, Calcium Phosphate Tribasic, SodiumCitrate, Magnesium Chloride, Magnesium Phosphate Dibasic, ArtificialFlavor, Sodium Chloride, Soy Lecithin, Choline Chloride, Ascorbic Acid,Carrageenan, Zinc Sulfate, Ferrous Sulfate, Alpha-Tocopheryl Acetate,Gellan Gum, Niacinamide, Calcium Pantothenate, Manganese Sulfate, CupricSulfate, Vitamin A Palmitate, Thiamine Chloride Hydrochloride,Pyridoxine Hydrochloride, Riboflavin, Folic Acid, Sodium Molybdate,Chromium Chloride, Biotin, Potassium Iodide, Sodium Selenate. (See alsoProSure®.)

B. ENSURE® BARS:

Usage: ENSURE BARS are complete, balanced nutrition for supplemental usebetween or with meals. They provide a delicious, nutrient-richalternative to other snacks. ENSURE BARS contain <1 g lactose/bar, andChocolate Fudge Brownie flavor is gluten-free. (Honey Graham Crunchflavor contains gluten.)

Patient Conditions:

-   -   For patients who need extra calories, protein, vitamins and        minerals.    -   Especially useful for people who do not take in enough calories        and nutrients.    -   For people who have the ability to chew and swallow    -   Not to be used by anyone with a peanut allergy or any type of        allergy to nuts.

Ingredients: Honey Graham Crunch—High-Fructose Corn Syrup, Soy ProteinIsolate, Brown Sugar, Honey, Maltodextrin (Corn), Crisp Rice (MilledRice, Sugar [Sucrose], Salt [Sodium Chloride] and Malt), Oat Bran,Partially Hydrogenated Cottonseed and Soy Oils, Soy Polysaccharide,Glycerine, Whey Protein Concentrate, Polydextrose, Fructose, CalciumCaseinate, Cocoa Powder, Artificial Flavors, Canola Oil, High-OleicSafflower Oil, Nonfat Dry Milk, Whey Powder, Soy Lecithin and Corn Oil.Manufactured in a facility that processes nuts.

Vitamins and Minerals: Calcium Phosphate Tribasic, Potassium PhosphateDibasic, Magnesium Oxide, Salt (Sodium Chloride), Potassium Chloride,Ascorbic Acid, Ferric Orthophosphate, Alpha-Tocopheryl Acetate,Niacinamide, Zinc Oxide, Calcium Pantothenate, Copper Gluconate,Manganese Sulfate, Riboflavin, Beta Carotene, Pyridoxine Hydrochloride,Thiamine Mononitrate, Folic Acid, Biotin, Chromium Chloride, PotassiumIodide, Sodium Selenate, Sodium Molybdate, Phylloquinone, Vitamin D3 andCyanocobalamin.

Protein: Honey Graham Crunch—The protein source is a blend of soyprotein isolate and milk proteins. Soy protein isolate 74% Milk proteins26%

Fat: Honey Graham Crunch—The fat source is a blend of partiallyhydrogenated cottonseed and soybean, canola, high oleic safflower, oils,and soy lecithin. Partially hydrogenated cottonseed & soybean oil 76% Canola oil 8% High-oleic safflower oil 8% Corn oil 4% Soy lecithin 4%

Carbohydrate: Honey Graham Crunch—The carbohydrate source is acombination of high-fructose corn syrup, brown sugar, maltodextrin,honey, crisp rice, glycerine, soy polysaccharide, and oat bran.High-fructose corn syrup 24% Brown sugar 21% Maltodextrin 12% Honey 11%Crisp rice  9% Glycerine  9% Soy Polysaccharide  7% Oat bran  7%

C. ENSURE® HIGH PROTEIN:

Usage: ENSURE HIGH PROTEIN is a concentrated, high-protein liquid fooddesigned for people who require additional calories, protein, vitamins,and minerals in their diets. It can be used as an oral nutritionalsupplement with or between meals or, in appropriate amounts, as a mealreplacement. ENSURE HIGH PROTEIN is lactose- and gluten-free, and issuitable for use by people recovering from general surgery or hipfractures and by patients at risk for pressure ulcers.

Patient Conditions:

-   -   For patients who require additional calories, protein, vitamins,        and minerals, such as patients recovering from general surgery        or hip fractures, patients at risk for pressure ulcers, and        patients on low-cholesterol diets.

Features:

-   -   Low in saturated fat    -   Contains 6 g of total fat and <5 mg of cholesterol per serving    -   Rich, creamy taste    -   Excellent source of protein, calcium, and other essential        vitamins and minerals    -   For low-cholesterol diets    -   Lactose-free, easily digested

Ingredients:

Vanilla Supreme: -D Water, Sugar (Sucrose), Maltodextrin (Corn), Calciumand Sodium Caseinates, High-OIeic Safflower Oil, Soy Protein Isolate,Soy Oil, Canola Oil, Potassium Citrate, Calcium Phosphate Tribasic,Sodium Citrate, Magnesium Chloride, Magnesium Phosphate Dibasic,Artificial Flavor, Sodium Chloride, Soy Lecithin, Choline Chloride,Ascorbic Acid, Carrageenan, Zinc Sulfate, Ferrous Suffate,Alpha-Tocopheryl Acetate, Gellan Gum, Niacinamide, Calcium Pantothenate,Manganese Sulfate, Cupric Sulfate, Vitamin A Palmitate, ThiamineChloride Hydrochloride, Pyridoxine Hydrochloride, Riboflavin, FolicAcid, Sodium Molybdate, Chromium Chloride, Biotin, Potassium Iodide,Sodium Selenate, Phylloquinone, Vitamin D3 and Cyanocobalamin.

Protein:

The protein source is a blend of two high-biologic-value proteins:casein and soy. Sodium and calcium caseinates 85% Soy protein isolate15%

Fat:

The fat source is a blend of three oils: high-oleic safflower, canola,and soy. High-oleic safflower oil 40% Canola oil 30% Soy oil 30%

The level of fat in ENSURE HIGH PROTEIN meets American Heart Association(AHA) guidelines. The 6 grams of fat in ENSURE HIGH PROTEIN represent24% of the total calories, with 2.6% of the fat being from saturatedfatty acids and 7.9% from polyunsaturated fatty acids. These values arewithin the AHA guidelines of <30% of total calories from fat, <10% ofthe calories from saturated fatty acids, and <10% of total calories frompolyunsaturated fatty acids.

Carbohydrate:

ENSURE HIGH PROTEIN contains a combination of maltodextrin and sucrose.The mild sweetness and flavor variety (vanilla supreme, chocolate royal,wild berry, and banana), plus VARI-FLAVORS® Flavor Pacs in pecan,cherry, strawberry, lemon, and orange, help to prevent flavor fatigueand aid in patient compliance.

Vanilla and Other Nonchocolate Flavors: Sucrose 60% Maltodextrin 40%

Chocolate: Sucrose 70% Maltodextrin 30%

D. ENSURE® LIGHT

Usage: ENSURE LIGHT is a low-fat liquid food designed for use as an oralnutritional supplement with or between meals. ENSURE LIGHT is lactose-and gluten-free, and is suitable for use in modified diets, includinglow-cholesterol diets.

Patient Conditions:

-   -   For normal-weight or overweight patients who need extra        nutrition in a supplement that contains 50% less fat and 20%        fewer calories than ENSURE.    -   For healthy adults who do not eat right and need extra        nutrition.

Features:

-   -   Low in fat and saturated fat    -   Contains 3 g of total fat per serving and <5 mg cholesterol    -   Rich, creamy taste    -   Excellent source of calcium and other essential vitamins and        minerals    -   For low-cholesterol diets    -   Lactose-free, easily digested

Ingredients:

French Vanilla: -D Water, Maltodextrin (Corn), Sugar (Sucrose), CalciumCaseinate, High-Oleic Safflower Oil, Canola Oil, Magnesium Chloride,Sodium Citrate, Potassium Citrate, Potassium Phosphate Dibasic,Magnesium Phosphate Dibasic, Natural and Artificial Flavor, CalciumPhosphate Tribasic, Cellulose Gel, Choline Chloride, Soy Lecithin,Carrageenan, Salt (Sodium Chloride), Ascorbic Acid, Cellulose Gum,Ferrous Sulfate, Alpha-Tocopheryl Acetate, Zinc Sulfate, Niacinamide,Manganese Sulfate, Calcium Pantothenate, Cupric Sulfate, ThiamineChloride Hydrochloride, Vitamin A Palmitate, Pyridoxine Hydrochloride,Riboflavin, Chromium Chloride, Folic Acid, Sodium Molybdate, Biotin,Potassium Iodide, Sodium Selenate, Phylloquinone, Vitamin D3 andCyanocobalamin.

Protein:

The protein source is calcium caseinate. Calcium caseinate 100%

Fat:

The fat source is a blend of two oils: high-oleic safflower and canola.High-oleic safflower oil 70% Canola oil 30%

The level of fat in ENSURE LIGHT meets American Heart Association (AHA)guidelines. The 3 grams of fat in ENSURE LIGHT represent 13.5% of thetotal calories, with 1.4% of the fat being from saturated fatty acidsand 2.6% from polyunsaturated fatty acids. These values are within theAHA guidelines of <30% of total calories from fat, <10% of the, caloriesfrom saturated fatty acids, and <10% of total calories frompolyunsaturated fatty acids.

Carbohydrate:

ENSURE LIGHT contains a combination of maltodextrin and sucrose. Thechocolate flavor contains corn syrup as well. The mild sweetness andflavor variety (French vanilla, chocolate supreme, strawberry swirl),plus VARI-FLAVORS® Flavor Pacs in pecan, cherry, strawberry, lemon, andorange, help to prevent flavor fatigue and aid in patient compliance.

Vanilla and Other Nonchocolate Flavors: Sucrose 51% Maltodextrin 49%

Chocolate: Sucrose 47.0% Corn Syrup 26.5% Maltodextrin 26.5%

Vitamins and Minerals:

An 8-fl-oz serving of ENSURE LIGHT provides at least 25% of the RDIs for24 key vitamins and minerals.

Caffeine:

Chocolate flavor contains 2.1 mg caffeine/8 fl oz.

E. ENSURE PLUS®

Usage: ENSURE PLUS is a high-calorie, low-residue liquid food for usewhen extra calories and nutrients, but a normal concentration ofprotein, are needed. It is designed primarily as an oral nutritionalsupplement to be used with or between meals or, in appropriate amounts,as a meal replacement. ENSURE PLUS is lactose- and gluten-free. Althoughit is primarily an oral nutritional supplement, it can be fed by tube.

Patient Conditions:

-   -   For patients who require extra calories and nutrients, but a        normal concentration of protein, in a limited volume.    -   For patients who need to gain or maintain healthy weight.

Features:

-   -   Rich, creamy taste    -   Good source of essential vitamins and minerals

Ingredients:

Vanilla: -D Water, Corn Syrup, Maltodextrin (Corn), Corn Oil, Sodium andCalcium Caseinates, Sugar (Sucrose), Soy Protein Isolate, MagnesiumChloride, Potassium Citrate, Calcium Phosphate Tribasic, Soy Lecithin,Natural and Artificial Flavor, Sodium Citrate, Potassium Chloride,Choline Chloride, Ascorbic Acid, Carrageenan, Zinc Sulfate, FerrousSulfate, Alpha-Tocopheryl Acetate, Niacinamide, Calcium Pantothenate,Manganese Sulfate, Cupric Sulfate, Thiamine Chloride Hydrochloride,Pyridoxine Hydrochloride, Riboflavin, Vitamin A Palmitate, Folic Acid,Biotin, Chromium Chloride, Sodium Molybdate, Potassium Iodide, SodiumSelenite, Phylloquinone, Cyanocobalamin and Vitamin D3.

Protein:

The protein source is a blend of two high-biologic-value proteins:casein and soy. Sodium and calcium caseinates 84% Soy protein isolate16%

Fat:

The fat source is corn oil. Corn oil 100%

Carbohydrate:

ENSURE PLUS contains a combination of maltodextrin and sucrose. The mildsweetness and flavor variety (vanilla, chocolate, strawberry, coffee,buffer pecan, and eggnog), plus VAR1-FLAVORS® Flavor Pacs in pecan,cherry, strawberry, lemon, and orange, help to prevent flavor fatigueand aid in patient compliance.

Vanilla, Strawberry, Butter Pecan, and Coffee Flavors: Corn Syrup 39%Maltodextrin 38% Sucrose 23%

Chocolate and Eggnog Flavors: Corn Syrup 36% Maltodextrin 34% Sucrose30%

Vitamins and Minerals:

An 8-fl-oz serving of ENSURE PLUS provides at least 15% of the RDIs for25 key Vitamins and minerals.

Caffeine:

Chocolate flavor contains 3.1 mg Caffeine/8 fl oz. Coffee flavorcontains a trace amount of caffeine.

F. ENSURE PLUS® HN

Usage: ENSURE PLUS HN is a nutritionally complete high-calorie,high-nitrogen liquid food designed for people with higher calorie andprotein needs or limited volume tolerance. It may be used for oralsupplementation or for total nutritional support by tube. ENSURE PLUS HNis lactose- and gluten-free.

Patient Conditions:

-   -   For patients with increased calorie and protein needs, such as        following surgery or injury.    -   For patients with limited volume tolerance and early satiety.

Features:

-   -   For supplemental or total nutrition    -   For oral or tube feeding    -   1.5 CaVmL,    -   High nitrogen    -   Calorically dense

Ingredients:

Vanilla: -D Water, Maltodextrin (Corn), Sodium and Calcium Caseinates,Corn Oil, Sugar (Sucrose), Soy Protein Isolate, Magnesium Chloride,Potassium Citrate, Calcium Phosphate Tribasic, Soy Lecithin, Natural andArtificial Flavor, Sodium Citrate, Choline Chloride, Ascorbic Acid,Taurine, L-Carnitine, Zinc Sulfate, Ferrous Sulfate, Alpha-TocopherylAcetate, Niacinamide, Carrageenan, Calcium Pantothenate, ManganeseSulfate, Cupric Sulfate, Thiamine Chloride Hydrochloride, PyridoxineHydrochloride, Riboflavin, Vitamin A Palmitate, Folic Acid, Biotin,Chromium Chloride, Sodium Molybdate, Potassium Iodide, Sodium Selenite,Phylloquinone, Cyanocobalamin and Vitamin D3.

G. ENSURE® POWDER:

Usage: ENSURE POWDER (reconstituted with water) is a low-residue liquidfood designed primarily as an oral nutritional supplement to be usedwith or between meals. ENSURE POWDER is lactose- and gluten-free, and issuitable for use in modified diets, including low-cholesterol diets.

Patient Conditions:

-   -   For patients on modified diets    -   For elderly patients at nutrition risk    -   For patients recovering from illness/surgery    -   For patients who need a low-residue diet

Features:

-   -   Convenient, easy to mix    -   Low in saturated fat    -   Contains 9 g of total fat and <5 mg of cholesterol per serving    -   High in vitamins and minerals    -   For low-cholesterol diets    -   Lactose-free, easily digested

Ingredients: -D Corn Syrup, Maltodextrin (Corn), Sugar (Sucrose), CornOil, Sodium and Calcium Caseinates, Soy Protein Isolate, ArtificialFlavor, Potassium Citrate, Magnesium Chloride, Sodium Citrate, CalciumPhosphate Tribasic, Potassium Chloride, Soy Lecithin, Ascorbic Acid,Choline Chloride, Zinc Sulfate, Ferrous Sulfate, Alpha-TocopherylAcetate, Niacinamide, Calcium Pantothenate, Manganese Sulfate, ThiamineChloride Hydrochloride, Cupric Sulfate, Pyridoxine Hydrochloride,Riboflavin, Vitamin A Palmitate, Folic Acid, Biotin, Sodium Molybdate,Chromium Chloride, Potassium Iodide, Sodium Selenate, Phylloquinone,Vitamin D3 and Cyanocobalamin.

Protein:

The protein source is a blend of two high-biologic-value proteins:casein and soy. Sodium and calcium caseinates 84% Soy protein isolate16%

Fat:

The fat source is corn oil. Corn oil 100%

Carbohydrate:

ENSURE POWDER contains a combination of corn syrup, maltodextrin, andsucrose. The mild sweetness of ENSURE POWDER, plus VARI-FLAVORS® FlavorPacs in pecan, cherry, strawberry, lemon, and orange, helps to preventflavor fatigue and aid in patient compliance.

Vanilla: Corn Syrup 35% Maltodextrin 35% Sucrose 30%

H. ENSURE® PUDDING

Usage: ENSURE PUDDING is a nutrient-dense supplement providing balancednutrition in a nonliquid form to be used with or between meals. It isappropriate for consistency-modified diets (e.g., soft, pureed, or fullliquid) or for people with swallowing impairments. ENSURE PUDDING isgluten-free.

Patient Conditions:

-   -   For patients on consistency-modified diets (e.g., soft, pureed,        or full liquid)    -   For patients with swallowing impairments

Features:

-   -   Rich and creamy, good taste    -   Good source of essential vitamins and minerals    -   Convenient-needs no refrigeration    -   Gluten-free

Nutrient Profile per 5 oz: Calories 250, Protein 10.9%, Total Fat 34.9%,Carbohydrate 54.2%

Ingredients:

Vanilla: -D Nonfat Milk, Water, Sugar (Sucrose), Partially HydrogenatedSoybean Oil, Modified Food Starch, Magnesium Sulfate, Sodium StearoylLactylate, Sodium Phosphate Dibasic, Artificial Flavor, Ascorbic Acid,Zinc Sulfate, Ferrous Sulfate, Alpha-Tocopheryl Acetate, CholineChloride, Niacinamide, Manganese Sulfate, Calcium Pantothenate, FD&CYellow #5, Potassium Citrate, Cupric Sulfate, Vitamin A Palmitate,Thiamine Chloride Hydrochloride, Pyridoxine Hydrochloride, Riboflavin,FD&C Yellow #6, Folic Acid, Biotin, Phylloquinone, Vitamin D3 andCyanocobalamin.

Protein:

The protein source is nonfat milk. Nonfat milk 100%

Fat:

The fat source is hydrogenated soybean oil. Hydrogenated soybean oil100%

Carbohydrate:

ENSURE PUDDING contains a combination of sucrose and modified foodstarch. The mild sweetness and flavor variety (vanilla, chocolate,butterscotch, and tapioca) help prevent flavor fatigue. The productcontains 9.2 grams of lactose per serving.

Vanilla and Other Nonchocolate Flavors: Sucrose 56% Lactose 27% Modifiedfood starch 17%

Chocolate: Sucrose 58% Lactose 26% Modified food starch 16%

I. ENSURE® WITH FIBER:

Usage: ENSURE WITH FIBER is a fiber-containing, nutritionally completeliquid food designed for people who can benefit from increased dietaryfiber and nutrients. ENSURE WITH FIBER is suitable for people who do notrequire a low-residue diet. It can be fed orally or by tube, and can beused as a nutritional supplement to a regular diet or, in appropriateamounts, as a meal replacement. ENSURE WITH FIBER is lactose- andgluten-free, and is suitable for use in modified diets, includinglow-cholesterol diets.

Patient Conditions:

-   -   For patients who can benefit from increased dietary fiber and        nutrients

Features:

-   -   New advanced formula-low in saturated fat, higher in vitamins        and minerals    -   Contains 6 g of total fat and <5 mg of cholesterol per serving    -   Rich, creamy taste    -   Good source of fiber    -   Excellent source of essential vitamins and minerals    -   For low-cholesterol diets    -   Lactose- and gluten-free

Ingredients:

Vanilla: -D Water; Maltodextrin (Corn), Sugar (Sucrose), Sodium andCalcium Caseinates, Oat Fiber, High-Oleic Safflower Oil, Canola Oil, SoyProtein Isolate, Corn Oil, Soy Fiber, Calcium Phosphate Tribasic,Magnesium Chloride, Potassium Citrate, Cellulose Gel, Soy Lecithin,Potassium Phosphate Dibasic, Sodium Citrate, Natural and ArtificialFlavors, Choline Chloride, Magnesium Phosphate, Ascorbic Acid, CelluloseGum, Potassium Chloride, Carrageenan, Ferrous Sulfate, Alpha-TocopherylAcetate, Zinc Sulfate, Niacinamide, Manganese Sulfate, CalciumPantothenate, Cupric Sulfate, Vitamin A Palmitate, Thiamine ChlorideHydrochloride, Pyridoxine Hydrochloride, Riboflavin, Folic Acid,Chromium Chloride, Biotin, Sodium Molybdate, Potassium Iodide, SodiumSelenate, Phylloquinone, Vitamin D3 and Cyanocobalamin.

Protein:

The protein source is a blend of two high-biologic-value proteins-caseinand soy. Sodium and calcium caseinates 80% Soy protein isolate 20%

Fat:

The fat source is a blend of three oils: high-oleic safflower, canola,and corn. High-oleic safflower oil 40% Canola oil 40% Corn oil 20%

The level of fat in ENSURE WITH FIBER meets American Heart Association(AHA) guidelines. The 6 grams of fat in ENSURE WITH FIBER represent 22%of the total calories, with 2.01% of the fat being from saturated fattyacids and 6.7% from polyunsaturated fatty acids. These values are withinthe AHA guidelines of ≦30% of total calories from fat, <10% of thecalories from saturated fatty acids, and ≦10% of total calories frompolyunsaturated fatty acids.

Carbohydrate:

ENSURE WITH FIBER contains a combination of maltodextrin and sucrose.The mild sweetness and flavor variety (vanilla, chocolate, and butterpecan), plus VARI-FLAVORS® Flavor Pacs in pecan, cherry, strawberry,lemon, and orange, help to prevent flavor fatigue and aid in patientcompliance.

Vanilla and Other Nonchocolate Flavors: Maltodextrin 66% Sucrose 25% OatFiber  7% Soy Fiber  2%

Chocolate: Maltodextrin 55% Sucrose 36% Oat Fiber  7% Soy Fiber  2%

Fiber:

The fiber blend used in ENSURE WITH FIBER consists of oat fiber and soypolysaccharide. This blend results in approximately 4 grams of totaldietary fiber per 8-fl. oz can. The ratio of insoluble to soluble fiberis 95:5.

The various nutritional supplements described above and known to othersof skill in the art can be substituted and/or supplemented with thePUFAs produced in accordance with the present invention.

J. Oxepa™ Nutritional Product

Oxepa is a low-carbohydrate, calorically dense, enteral nutritionalproduct designed for the dietary management of patients with or at riskfor ARDS. It has a unique combination of ingredients, including apatented oil blend containing eicosapentaenoic acid (EPA from fish oil),γ-linolenic acid (GLA from borage oil), and elevated antioxidant levels.

Caloric Distribution:

Caloric density is high at 1.5 Cal/mL (355 Cal/8 fl oz), to minimize thevolume required to meet energy needs.

The distribution of Calories in Oxepa is shown in Table A. TABLE ACaloric Distribution of Oxepa per 8 fl oz. per liter % of Cal Calories355 1,500 — Fat (g) 22.2 93.7 55.2 Carbohydrate (g) 25 105.5 28.1Protein (g) 14.8 62.5 16.7 Water (g) 186 785 —

Fat:

-   -   Oxepa contains 22.2 g of fat per 8-fl oz serving (93.7 g/L).    -   The fat source is an oil blend of 31.8% canola oil, 25%        medium-chain triglycerides (MCTs), 20% borage oil, 20% fish oil,        and 3.2% soy lecithin. The typical fatty acid profile of Oxepa        is shown in Table B.    -   Oxepa provides a balanced amount of polyunsaturated,        monounsaturated, and saturated fatty acids, as shown in Table        VI.    -   Medium-chain trigylcerides (MCTs)—25% of the fat blend—aid        gastric emptying because they are absorbed by the intestinal        tract without emulsification by bile acids.

The various fatty acid components of Oxepa™ nutritional product can besubstituted and/or supplemented with the PUFAs produced in accordancewith this invention. TABLE B Typical Fatty Acid Profile Fatty Acids %Total g/8 fl oz* 9/L* Caproic (6:0) 0.2 0.04 0.18 Caprylic (8:0) 14.693.1 13.07 Capric (10:0) 11.06 2.33 9.87 Palmitic (16:0) 5.59 1.18 4.98Palmitoleic 1.82 0.38 1.62 Stearic 1.94 0.39 1.64 Oleic 24.44 5.16 21.75Linoleic 16.28 3.44 14.49 α-Linolenic 3.47 0.73 3.09 γ-Linolenic 4.821.02 4.29 Eicosapentaenoic 5.11 1.08 4.55 n-3-Docosapentaenoic 0.55 0.120.49 Docosahexaenoic 2.27 0.48 2.02 Others 7.55 1.52 6.72

Fatty acids equal approximately 95% of total fat. TABLE C Fat Profile ofOxepa. % of total calories from fat 55.2 Polyunsaturated fatty acids31.44 g/L Monounsaturated fatty acids 25.53 g/L Saturated fatty acids32.38 g/L n-6 to n-3 ratio 1.75:1 Cholesterol 9.49 mg/8 fl oz 40.1 mg/L

Carbohydrate:

-   -   The carbohydrate content is 25.0 g per 8-fl-oz serving (105.5        g/L).    -   The carbohydrate sources are 45% maltodextrin (a complex        carbohydrate) and 55% sucrose (a simple sugar), both of which        are readily digested and absorbed.    -   The high-fat and low-carbohydrate content of Oxepa is designed        to minimize carbon dioxide (CO2) production. High CO2 levels can        complicate weaning in ventilator-dependent patients. The low        level of carbohydrate also may be useful for those patients who        have developed stress-induced hyperglycemia.    -   Oxepa is lactose-free.

Dietary carbohydrate, the amino acids from protein, and the glycerolmoiety of fats can be converted to glucose within the body. Throughoutthis process, the carbohydrate requirements of glucose-dependent tissues(such as the central nervous system and red blood cells) are met.However, a diet free of carbohydrates can lead to ketosis, excessivecatabolism of tissue protein, and loss of fluid and electrolytes. Theseeffects can be prevented by daily ingestion of 50 to 100 g of digestiblecarbohydrate, if caloric intake is adequate. The carbohydrate level inOxepa is also sufficient to minimize gluconeogenesis, if energy needsare being met.

Protein:

-   -   Oxepa contains 14.8 g of protein per 8-fl-oz serving (62.5 g/L).    -   The total calorie/nitrogen ratio (150:1) meets the need of        stressed patients.    -   Oxepa provides enough protein to promote anabolism and the        maintenance of lean body mass without precipitating respiratory        problems. High protein intakes are a concern in patients with        respiratory insufficiency. Although protein has little effect on        CO₂ production, a high protein diet will increase ventilatory        drive.    -   The protein sources of Oxepa are 86.8% sodium caseinate and        13.2% calcium caseinate.    -   The amino acid profile of the protein system in Oxepa meets or        surpasses the standard for high quality protein set by the        National Academy of Sciences.    -   Oxepa is gluten-free.

The present invention may be illustrated by use of the followingnon-limiting examples:

EXAMPLE I Design of Degenerate Oligonucleotides for the Isolation ofDesaturases from Delacroixia coronata (ATCC 28565) and cDNA Synthesis

The fatty acid composition analysis of the fungus Delacroixia coronata(D. coronata) (ATCC 28565) was investigated to determine the types andamounts of polyunsaturated fatty acids (PUFAs) it produced. This funguswas found to contain significant amounts (˜19% of total lipid) of thePUFA arachidonic acid (ARA, C20:4n-6) (see FIG. 1). Thus, it wasdetermined that D. coronata probably contains a Δ6-desaturase whichconverts linoleic acid (LA, C18:2n-6) to γ-linolenic acid (GLA,C18:3n-6) and a Δ5-desaturase which converts dihomo-γ-linolenic acid(DGLA, C20:3n-6) to ARA. The goal was therefore to isolate the predicteddesaturase genes from D. coronata and to verify the functionality of theenzymes by expression in an alternate host.

The approach taken was to design degenerate oligonucleotides (primers)that represent amino acid motifs that are conserved in known front-enddesaturases. These primers could be then used in a PCR reaction toidentify a gene fragment containing the conserved regions present in theputative desaturase genes from Delacroixia. Since the only fungaldesaturases identified, at the time, were the Δ5- and Δ6-desaturasegenes from Mortierella alpina (Genbank accession numbers AF067650,AB020032, respectively), desaturase sequences from plants as well asanimals were taken into consideration during the design of thesedegenerate primers. In particular, known Δ5- and Δ6-desaturase sequencesfrom the following organisms were used for the design of thesedegenerate primers: Mortierella alpina, Borago officinalis, Helianthusannuus, Brassica napus, Dictyostelium discoideum, Rattus norvegicus, Musmusculus, Homo sapiens, Caenorhabditis elegans, Arabidopsis thaliana,and Ricinus communis. The degenerate primers used were as follows usingthe CODEHOP™ Blockmaker program (http://blocks.fhcrc.org/codehop.html):

-   -   a. Protein motif 1 (SEQ ID NO:7): NH₃— VYDVTEWVKRHPGG —COOH

Primer RO834 (SEQ ID NO:8):5′-GTBTAYGAYGTBACCGARTGGGTBAAGCGYCAYCCBGGHGGH-3′

-   -   b. Protein Motif 2 (SEQ ID NO:9): NH₃— GASANWWKHQHNVHH —COOH

Primer RO835 (Forward)(SEQ ID NO:10):5′-GGHGCYTCCGCYAACTGGTGGAAGCAYCAGCAYAACGTBCAYCAY- 3′

Primer RO836 (Reverse)(SEQ ID NO:11):5′-RTGRTGVACGTTRTGCTGRTGCTTCCACCAGTTRGCGGARGCDCC- 3′

-   -   c. Protein Motif 3 (SEQ ID NO:12): NH₃—NYQIEHHLFPTM —COOH

Primer RO838 (Reverse)(SEQ ID NO:13):5′-TTGATRGTCTARCTYGTRGTRGASAARGGVTGGTAC-3′

All known desaturase amino acid sequences have a tripartite motifcomprised of a group of eight conserved histidines:HX₍₃₋₄₎HX₍₇₋₄₁₎HX₍₂₋₃₎HHX₍₆₁₋₁₈₉₎HX₍₂₋₃₎HH. The three histidine boxesare often used to identify putative desaturases. In addition, two moreprimers were designed based on the 2nd and 3rd conserved ‘Histidine-box’found in known Δ6-desaturases. These were:

Primer RO753 (SEQ ID NO:14) 5′-CATCATCATXGGRAAXARRTGRTG-3′

Primer RO754 (SEQ ID NO:15): 5′-CTACTACTACTACAYCAYACXTAY ACXAAY-3′.The degeneracy code for the oligonucleotide sequences was: B=C,G,T;H=A,C,T; S=C,G; R=A,G; V=A,C,G; Y=C,T; D=A,T,C; X=A,C,G,T

To isolate genes encoding functional desaturase enzymes, the RNA wasfirst prepared. D. coronata (ATCC 28565) cells were grown in BY+Media(#790, Difco, Detroit, Mich.) at room temperature for 4 days, in thepresence of light, and with constant agitation (250 rpm) to obtain themaximum biomass. These cells were harvested by centrifugation at 5000rpm for 10 minutes and rinsed in ice-cold RNase-free water. These cellswere then lysed in a French press at 10,000 psi, and the lysed cellswere directly collected into TE buffered phenol. Proteins from the celllysate were removed by repeated phenol:chloroform (1:1 v/v) extraction,followed by a chloroform extraction. The nucleic acids from the aqueousphase were precipitated at −70° C. for 30 minutes using 0.3 M (finalconcentration) sodium acetate (pH 5.6) and one volume of isopropanol.The precipitated nucleic acids were collected by centrifugation at15,000 rpm for 30 minutes at 4° C., vacuum-dried for 5 minutes and thentreated with DNaseI (RNase-free) in 1× DNase buffer (20 mM Tris-Cl, pH8.0; 5 mM MgCl₂) for 15 minutes at room temperature. The reaction wasquenched with 5 mM EDTA (pH 8.0) and the RNA further purified using theQiagen RNeasy Maxi kit (Qiagen, Valencia, Calif.), as per themanufacturer's protocol.

To prepare the cDNA, two PCR reactions were performed. The first PCRreaction was performed using the SuperScript Preamplification System forFirst Strand cDNA Synthesis Kit (Life Technologies, Rockville, Md.),with 0.5 μg of oligo dT primer and 5 μl RNA (1 μg/l), following themanufacturer's instructions. The second PCR reaction was performed usingthe degenerate primers RO834/RO838 (designed with the block makerprogram) and the first strand cDNA as target, in Perkin Elmer 9600. ThePCR components were as follows: 2 μl of the first strand cDNA template,1 μl 50× dNTP mix, 0.2 μM final concentration of each primer, 5 μl 10×KlenTaq PCR reaction buffer, and 1 μl of Advantage KlenTaq polymerase(Clonetech, Palo Alto, Calif.). Thermocycling was carried out asfollows: an initial denaturation at 94° C. for 3 minutes, followed by 35cycles of denaturation at 94° C. for 30 seconds; annealing at 60° C. for30 seconds; and extension at 72° C. for 7 minute. This was followed by afinal extension at 72° C. for 7 minutes. The reaction was separated on a1% agarose gel, and approximately 1.3 Kb DNA fragment was excised andpurified with the QiaQuick Gel Extraction Kit (Qiagen, Valencia,Calif.). The staggered ends on this fragment were ‘filled-in’ using T4DNA polymerase (Life Technologies, Rockville, Md.) as per manufacturer'sspecifications, and this DNA fragment was cloned into the PCR-Bluntvector (Invitrogen, Carlsbad, Calif.). The recombinant plasmids weretransformed into TOP10 supercompetent cells (Invitrogen, Carlsbad,Calif.) and 9 clones were partially sequenced. Three separateoverlapping clones aligned to give a sequence of approximately 1080 bp(FIG. 2).

The translated sequence corresponding to this fragment (FIG. 3) was usedto search the GenBank database. This fragment was found to share highestsequence homology with the Mortierella alpina Δ6-desaturase (Genbankaccession # AF110510) (˜53% sequence identity) (FIG. 4). Thus, thefull-length gene encoding this putative desaturase was isolated todetermine its activity when expressed in yeast.

EXAMPLE II Preparation of RACE cDNA and Isolation of the Full LengthGene Sequence From Delacroixia coronata (ATCC 28565)

RACE (rapid amplification of cDNA ends) ready cDNA was used as a targetfor the reactions to isolate the full-length cDNA. To prepare RACE readycDNA, approximately 5 μg of total RNA was used according to themanufacturer's direction with the GeneRacer™ kit (Invitrogen, Carlsbad,Calif.) and Superscript II™ enzyme (Invitrogen, Carlsbad, Calif.) forreverse transcription to produce cDNA target. For the initialamplification of the ends, the following thermocycling protocol was usedin a Perkin Elmer 9600: initial melt at 94° C. for 2 minutes followed by5 cycles of 94° C. for 30 seconds and 72° C. for 3 minutes, 10 cycles of94° C. 30 seconds, 70° C. for 30 seconds, and 72° C. for 3 minutes and20 cycles of 94° C. for 30 seconds, 68° C. for 30 seconds and 72° C. for3 minutes, followed by an extension of 72° C. for 10 minutes.

The first PCR reactions were performed with 10 pMol of RO1526 (SEQ IDNO:16)(5′-TGC CTC CGT ATT CTC CCT TAA CCA CAA C-3′) or RO1528 (SEQ IDNO:17)(5′-CTT CCA CAC TTT CCA CCC TGA TTC TTC CTG-3′) and 30 pMolGeneRacer™ 3 prime primer (SEQ ID NO:18)(5′-GCT GTC AAC GAT ACG CTA CGTAAC G-3′); or RO1524 (SEQ ID NO:19)(5′-TGA ATC CAA GTG GAG GGC ATG AAGACA G-3′) or RO1525 (SEQ ID NO:20)(5′-CGG AGG GGA TGA TAC CAA ACC AACTAG AGC-3′) and GeneRacer™ 5 prime primer (SEQ ID NO:21)(5′-CGA CTG GAGCAC GAG GAC ACT GA-3′). Each reaction contained 1 ul of cDNA in a finalvolume of 50 ul with Platimum Taq™ PCRx (Clonetech, Palo Alto, Calif.)using MgSO₄ according to the manufacturer's directions. A nestedreaction was performed with 1 μl of the initial reaction, 10 pmol ofnested primer RO1524 or RO1525 and 30 pmol of the GeneRacer™ nested 5prime primer (SEQ ID NO:22)(5′-GGA CAC TGA CAT GGA CTG AAG GAG TA-3′);or nested primer RO1526 or RO1528 and GeneRacer™ nested 3 prime primer(SEQ ID NO:23)(5′-CGC TAC GTA ACG GCA TGA CAG TG-3′) using the sameconditions as the first reaction. Agarose gel analysis of the PCRproducts showed bands from approximately 400 bp to 1.3 Kb for the fourreactions. Subsequent cloning into pCR Blunt (Invitrogen, Carlsbad,Calif.), transformation into Top10 competent cells (Invitrogen,Carlsbad, Calif.), and sequencing revealed an open reading frame of 466amino acids. Based on the alignment with M. alpina Δ6-desaturase, it wasprobable that this sequence contained the entire gene and that it wasvery likely a Δ6-desaturase. However, the translated amino acid sequencedid not contain a start codon methionine (Met-ATG) at an appropriatesite when aligned with the M. alpina Δ6-desaturase or some other fungalΔ6-desaturases.

Three alternative start codons were created at various sites on thisputative desaturase gene (FIG. 5). The full-length genes with thesealternate start codons were designated pRDC8, pRDC10 and pRDC12 (FIG.5). To create pRDC8, PCR was carried out using RACE cDNA using thefollowing primers:

(Stop-Ala, DraI)-Forward primer (SEQ ID NO:24): (5′-TTT AAA ATG AAT GGTAAT AAA ATT GCG GCG ATA AAA G-3′), and Reverse Primer (SEQ ID NO:25):(5′-CTA GCT AGC TTA AAT TTG GTC GTT GAT ATT GGT GGC-3′). PCR reactionswere performed according to the manufacturer's directions using thePlatinum Pfx Polymerase (Invitrogen, Carlsbad, Calif.). The full-lengthPCR product was digested with NheI and cloned into EcoRI-blunted (5′)and Nhe1 (3′) sites of the pYX242 vector. This sequence utilized the‘Met’ present upstream of the stop codon (SEQ ID NO:26)(MNGNKI*AIKEGAIL. . . . ) as the start site, and the stop codon was converted to an‘Ala’ resulting in the 5′ seq (SEQ ID NO:27)(MNGNKIAAIKEGAIL . . . . )(FIG. 5, FIG. 6 and FIG. 7).

To create pRDC10, PCR was carried out using RACE cDNA using thefollowing primers:

(Ala-Met, Dra1) Forward primer (SEQ ID NO:28): (5′-TTT AAA ATG ATA AAAGAA GGG GCA ATA TTA ACC-3′), and Reverse Primer (SEQ ID NO:29): (5′-CTAGCT AGC TTA AAT TTG GTC GTT GAT ATT GGT GGC-3′).

The PCR reactions were performed according to the manufacturer'sdirections, using Platinum Pfx Polymerase (Invitrogen, Carlsbad,Calif.). The full-length PCR product was digested with NheI and clonedinto EcoRI-blunted (5′) and Nhe1 (3′) sites of the pYX242 vector. Thisconverted the first Ala after the stop codon (SEQ ID NO:30) (*AIKEGAIL .. . ) to a Met (SEQ ID NO:31)(*MIKEGAIL . . . ), and this clone wasdesignated as pRDC10 (FIG. 5, FIG. 8 & FIG. 9).

To isolate pRDC12, genomic DNA (gDNA) was prepared using the DNeasyplant mini kit according to the manufacturer's directions (Qiagen,Valencia, Calif.). Primer RO1585 (SEQ ID NO:32)(5′-AAA GGA TCC AAT ATGTTA ATA GGC GGC GTT AAG-3′) was designed to convert the third isoleucineafter the stop codon (SEQ ID NO:33) (*AIKEGAILTFIL . . . . ) to amethionine (SEQ ID NO:34) (*AIKEGAILTFML . . . . ) (FIG. 5, FIG. 10 &FIG. 11). Primer RO1584 (SEQ ID NO:35)(5′-ATC CTC GAG TTA AAT TTG GTCGTT GAT ATT GGT G-3′) was designed for the 3′ end of the full-lengthcDNA sequence. The PCR components were as follows: 3 μl of the gDNA, 1μl 50× dNTP mix, 0.2 pM final concentration of primers RO1583 and RO1584or RO1585 and RO1584, 2 μl MgSO₄, 5 μl 10×PCR reaction buffer, and 0.2μl of platinum TAQ HF polymerase (Clonetech, Palo Alto, Calif.). Thefollowing thermocycling protocol was used in a Perkin Elmer 9600:initial melt at 94° C. for 2 minutes followed by 5 cycles of 94° C. for30 seconds and 72° C. for 3 minutes, 10 cycles of 94° C. 30 seconds, 70°C. for 30 seconds, and 72° C. for 3 minutes and 20 cycles of 94° C. for30 seconds, 68° C. for 30 seconds and 72° C. for 3 minutes, followed byan extension of 72° C. for 10 minutes. The reaction was separated on a1% agarose gel, and approximately 1.4 Kb DNA fragment was excised andpurified with the QiaQuick Gel Extraction Kit (Qiagen, Valencia,Calif.). The full-length PCR product designated Del-D6, was digestedwith BamHI/XhoI and cloned into pESC-Ura vector. This construct wasdesignated as pRDC-12. (Plasmid pRDC-12 was deposited with the AmericanType Culture Collection, 10801 University Boulevard, Manassas, Va. 20110on May 18, 2004 and was accorded accession number PTA-5975). Alignmentof the amino acid sequence of this putative desaturase (Del-D6) encodedby pRDC-12, with the Δ6-desaturase sequence from Mortierella alpina,revealed these proteins to share ˜51% sequence identity with each other(FIG. 12).

Like other front-end desaturases, Del-D6 contains the three conserved‘histidine boxes’ known to be required for the catalytic activity ofthese front end desaturase enzymes (Shanklin et al., Biochemistry 33(43):12787-94 (1994), Sayanova et al., Plant Physiol. 121(2):641-46(1999), and Periera et al., Prostaglandins Leukot. Essent. Fatty Acids68(2):97-106 (2003)) (FIG. 13).

-   Histidine Box 1 (SEQ ID NO:36): HDFLH-   Histidine Box 2 (SEQ ID NO:37): HNTHH-   Histidine Box 3 (SEQ ID NO:38): QVEHH    In addition, this sequence also contained a cytochrome b5 domain at    the 5′-end (HPGG motif (SEQ ID NO:39))(FIG. 13) implying that it    uses cytochrome b5 as an electron donor during the desaturation    reaction, as seen with other fungal and algal Δ6-desaturases    (Periera et al., Prostaglandins Leukot. Essent. Fatty Acids    68(2):97-106 (2003)). The overall G+C content of this gene is 41.9%.

EXAMPLE III Expression of Plasmids Containing Putative Desaturases inYeast

All three plasmids were transformed into competent Saccharomycescerevisiae strain 334. Yeast transformation was carried out using theAlkali-Cation Yeast Transformation Kit (BIO 101, Vista, Calif.)according to conditions specified by the manufacturer. Transformantswere selected for uracil auxotrophy on media lacking uracil (DOB[-Ura]). To detect the specific desaturase activity of these clones,transformants were grown in the presence of 50 μM specific fatty acidsubstrates as listed below:

-   -   a. Linoleic acid (LA, C18:2n-6) (conversion to α-linolenic acid        would indicate Δ15-desaturase activity and conversion to        γ-linolenic acid would indicate Δ6-desaturase activity);    -   b. Alphα-linolenic acid (ALA, C18:3n-3) (conversion to        stearidonic acid would indicate Δ6-desaturase activity);    -   c. (C20:2n-6) (conversion to dihomo-gammα-linolenic acid would        indicate A8-desaturase activity);    -   d. (C20:3n-3) (conversion to eicosatetraenoic acid would        indicate A8-desaturase activity);    -   e. Dihomo-γ-linolenic acid (DGLA, C20:3n-6) (conversion to        arachidonic acid would indicate Δ8-desaturase activity);    -   f. Eicosatetraenoic acid (ETA, C20:4n-3) (conversion to        eicosapentaenoic acid would indicate Δ5-activity);    -   g. Adrenic acid (ADA, C22:4n-6) (conversion to        ω6-docosapentaenoic acid would indicate Δ4-desaturase activity);        and    -   h. ω3-docosapentaenoic acid (DPA, C22:4n-6) (conversion to        docosahexaenoic acid would indicate Δ4-desaturase activity).        The negative control strain was S. cerevisiae 334 containing the        unaltered pYX242 vector, and these were grown simultaneously.

The cultures were vigorously agitated (250 rpm) and grown for 48 hours a24° C. in the presence of 50 μM (final concentration) of the varioussubstrates in 50 ml of media lacking uracil after inoculation withovernight growth of single colonies in yeast peptone dextrose broth(YPD) at 30° C. The cells were pelleted, and the pellets vortexed inmethanol; chloroform was added along with tridecanoin (as an internalstandard). These mixtures were incubated for at least an hour at roomtemperature or at 4° C. overnight. The chloroform layer was extractedand filtered through a Whatman filter with 1 gm anhydrous sodium sulfateto remove particulates and residual water. The organic solvents wereevaporated at 40° C. under a stream of nitrogen. The extracted lipidswere then derivitized to fatty acid methyl esters (FAME) for gaschromatography analysis (GC) by adding 2 ml of 0.5 N potassium hydroxidein methanol to a closed tube. The samples were heated to 95° C.-100° C.for 30 minutes and cooled to room temperature. Approximately 2 ml of 14%borontrifluoride in methanol was added and the heating repeated. Afterthe extracted lipid mixture cooled, 2 ml of water and 1 ml of hexanewere added to extract the fatty acid methyl esters (FAME) for analysisby GC. The percent conversion was calculated by dividing the productproduced by the sum of (the product produced+the substrate added) andthen multiplying by 100.

The results showed conversion of LA to GLA and ALA to STA. This wouldindicate Δ6-desaturase activity (see Table 1). TABLE 1 PercentConversion of Different Substrate Concentrations to Product pYX242Control PRDC8 pRDC10 pRDC12 C18:2n-6 → 0 4.1 4.6 35.1 C18:3n-6 C20:2n-6→ 0 0 0 0 C20:3n-6 C20:3n-6 → 0 0 0 0 C20:4n-6 C22:4n-6 → 0 0 0 0C22:5n-6 C18:3n-3 → 0.7 5 6 34.5 C18:4n-3 C20:3n-3 → 0 0 0 0 C20:4n-3C20:4n-3 → 0 0 0 0 C20:5n-3 C22:5n-3 → 0 0 0 0 C22:6n-3C18:2n-6 to C18:3n-6 (Linolenic acid to α-linolenic acid)C18:3n-3 to C18:4n-3 (α-linolenic acid to stearidonic acid)This data shows unequivocally that this gene indeed encodes aΔ6-desaturase, with no Δ5-, Δ8- or Δ4-desaturase activity.

EXAMPLE IV Co-Expression of Del-D6 (Δ6-desaturase from Delacroixia) withthe Mortierella alpina Elongase in Yeast

The plasmid pRDC-12 was co-transformed with pRSP-46, a clone thatcontains a M. alpina elongase gene from pRPBG-2 (see U.S. publishedpatent application no. U.S. 2003/0177508A1 incorporated herein in itsentirety by reference). Table 2 shows that when 50 μM of the substrateLA (C18:2n-6) was added, the desaturase converted the LA to GLA, and theelongase was able to add two carbons to GLA to produce DGLA. No DGLA wasproduced by the control transformation 334(pYX242/pESC-Ura). Also, when50 μM of the substrate ALA (18:3n-3) was added, the desaturase convertedthe ALA to STA, and the elongase was able to add two carbons to STA toproduce ETA. No ETA was produced by the control transformation334(pYX242/pESC-Ura). Thus, D. coronata Δ6-desaturase was able toproduce a product in a heterologous expression system that was thesubstrate of another heterologous enzyme (the M. alpina elongase) fromthe PUFA biosynthetic pathway to produce the expected PUFA. Thisdemonstrates that Δ6-desaturase can indeed work with other heterologousenzymes in the PUFA pathway in a heterologous expression system such asyeast. TABLE 2 Percent Conversion of Different Substrate Concentrationsto Product Substrate Desaturated Elongated incorporated product productPYX242/ 62.45 0 0 pESC-Ura (control) + LA pRDC-12/ 59.2 24.15 6.88pRSP-46 (elongase) + LA pYX242/ 37.25 0 0 pESC-Ura (control) + ALApRDC-12/ 67.82 19.75 5.84 pRSP-46 (elongase) + ALA

EXAMPLE V Identification of Δ6-Desaturase Homologues from OtherPUFA-Producing Organisms

Δ6-desaturases are predicted to exist in a number of PUFA-producingfungi and algae based on the presence of GLA (18:3n-6), ARA (20:4n-6)and/or EPA (20:5n-3) in these organisms upon analysis of their totalfatty acid profiles. Using the degenerate primers set RO834 (SEQ IDNO:8) and RO838 (SEQ ID NO:13) in a PCR reaction similar to thatdescribed in Example I, it is possible to isolate fragmentscorresponding to the Δ6-desaturase genes from these organisms, followedby the full-length gene isolation using the protocol described inExample I. Organisms that can be used to isolate Δ6-desaturase geneswould belong to the genera: Fungi such as Cunninghamella, Rhizopus,Gongronella, Allamyces, Synchytrium, Achlya, Phycomyces, Choanephora,Helicostylum, Entomopthora; Microalgae such as Chlorella, Dunaliella,Lauderia, Fucus, Sargassum, Layengaria, Colpomenia, Plocamium,Rhodomella, Gelidium, Polysiphonia, Chondrus (Folia Microbiol. (1992)37: 357-359, Stredanska S. & Sajbidor J.; Appl. Microbiol. Biotechnol.(1991) 35: 421-430, Radwan S. S.; Biochum. Biophys. ACTA (1965) 98:230-237, Shaw R.).

1. An isolated nucleic acid sequence or fragment thereof comprising orcomplementary to a nucleotide sequence encoding a polypeptide havingdesaturase activity, wherein the amino acid sequence of said polypeptidehas at least 90% identity to an amino acid sequence selected from thegroup consisting of SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6 and SEQ IDNO:8.
 2. An isolated nucleic acid sequence or fragment thereofcomprising or complementary to a nucleotide sequence having at least 90%identity to a nucleotide sequence selected from the group consisting ofSEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:5 and SEQ ID NO:7.
 3. The isolatednucleic acid sequence of claim 1 or claim 2 wherein said sequenceencodes a functionally active desaturase which utilizes amonounsaturated or polyunsaturated fatty acid as a substrate.
 4. Thenucleotide sequence of claim 1 or 2 wherein said sequence is isolatedfrom a fungus.
 5. The nucleotide sequence of claim 4 wherein said fungusis Delacroixia coronata.
 6. A purified polypeptide encoded by saidnucleotide sequence of claims 1 or
 2. 7. A purified polypeptide whichdesaturates polyunsaturated fatty acids at carbon 6 and comprises anamino acid sequence having at least 90% identity to an amino acidsequence selected from the group consisting of SEQ ID NO:2, SEQ ID NO:4,SEQ ID NO:6 and SEQ ID NO:8.
 8. A method of producing a desaturasecomprising the steps of: a) isolating a nucleic acid sequence comprisingor complementary to a nucleotide sequence: i) encoding a polypeptidecomprising an amino acid sequence having at least 90% identity to anamino acid sequence selected from the group consisting of SEQ ID NO:2,SEQ ID NO:4, SEQ ID NO:6 and SEQ ID NO:8 or ii) having at least 90%identity to a nucleotide sequence selected from the group consisting ofSEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:5 and SEQ ID NO:7; b) constructing avector comprising: i) said isolated nucleotide sequence operably linkedto ii) a regulatory sequence; c) introducing said vector into a hostcell for a time and under conditions sufficient for expression of saiddesaturase.
 9. A vector comprising: a) an isolated nucleic acid sequencecomprising or complementary to a nucleotide sequence: i) encoding apolypeptide comprising an amino acid sequence having at least 90%identity to an amino acid sequence selected from the group consisting ofSEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6 and SEQ ID NO:8 or ii) having atleast 90% identity to a nucleotide sequence selected from the groupconsisting of SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:5 and SEQ ID NO:7,operably linked to b) a regulatory sequence.
 10. A host cell comprisingsaid vector of claim
 9. 11. An isolated plant cell, plant or planttissue comprising said vector of claim 9, wherein expression of saidnucleotide sequence of said vector results in production of apolyunsaturated fatty acid by said plant cell, plant or plant tissue.12. The plant cell, plant or plant tissue of claim 11 wherein saidpolyunsaturated fatty acid is selected from the group consisting ofγ-linolenic acid and stearidonic acid.
 13. One or more plant fatty acidsexpressed by said plant cell, plant or plant tissue of claim
 11. 14. Atransgenic plant comprising said vector of claim 9, wherein expressionof said nucleotide sequence of said vector results in production of apolyunsaturated fatty acid in seeds of said transgenic plant.
 15. Amethod for producing a polyunsaturated fatty acid comprising the stepsof: a) isolating a nucleic acid sequence comprising or complementary toa nucleotide sequence: i) encoding a polypeptide comprising an aminoacid sequence having at least 90% identity to an amino acid sequenceselected from the group consisting of SEQ ID NO:2, SEQ ID NO:4, SEQ IDNO:6 and SEQ ID NO:8 or ii) having at least 90% identity to a nucleotidesequence selected from the group consisting of SEQ ID NO:1, SEQ ID NO:3,SEQ ID NO:5 and SEQ ID NO:7; b) constructing a vector comprising saidisolated nucleotide sequence; c) introducing said vector into a hostcell for a time and under conditions sufficient for expression of aΔ6-desaturase; and d) exposing said expressed Δ6-desaturase to asubstrate polyunsaturated fatty acid in order to convert said substrateto a product polyunsaturated fatty acid.
 16. The method according toclaim 15, wherein said substrate polyunsaturated fatty acid is linoleicacid or α-linolenic acid and said product polyunsaturated fatty acid isγ-linolenic acid or stearidonic acid, respectively.
 17. The methodaccording to claim 15 further comprising the step of exposing saidproduct polyunsaturated fatty acid to an elongase in order to convertsaid product polyunsaturated fatty acid to another polyunsaturated fattyacid.
 18. The method according to claim 17 wherein said productpolyunsaturated fatty acid is γ-linolenic acid or stearidonic acid andsaid another polyunsaturated fatty acid is dihomo-γ-linolenic acid oreicosatetraenoic acid, respectively.
 19. A method of producing apolyunsaturated fatty acid comprising the steps of: a) exposing asubstrate monounsaturated or polyunsaturated fatty acid to a desaturasein order to convert said substrate to a product polyunsaturated fattyacid; and b) exposing said product polyunsaturated fatty acid of step a)to a Δ6-desaturase comprising an amino acid sequence selected from thegroup consisting of SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6 and SEQ IDNO:8 in order to convert said product polyunsaturated fatty acid to afinal product polyunsaturated fatty acid.
 20. The method of claim 19wherein said substrate monounsaturated fatty acid is oleic acid and saidpolyunsaturated fatty acid is linoleic acid.
 21. The method of claim 19wherein said final product polyunsaturated fatty acid is γ-linolenicacid or stearidonic acid.
 22. A composition comprising at least onepolyunsaturated fatty acid selected from the group consisting of saidproduct polyunsaturated fatty acid produced according to the method of15 and said another polyunsaturated fatty acid produced according to themethod of claim
 17. 23. The composition of claim 22 wherein said productpolyunsaturated fatty acid is at least one polyunsaturated fatty acidselected from the group consisting of γ-linolenic acid or stearidonicacid.
 24. The composition of claim 22 wherein said anotherpolyunsaturated fatty acid is dihomo-γ-linolenic acid oreicosatetraenoic acid.
 25. The composition of claim 22 wherein saidcomposition is selected from the group consisting of an infant formula,a dietary supplement and a dietary substitute.
 26. The composition ofclaim 22 wherein said composition is administered to a human or ananimal.
 27. The composition of claim 26 wherein said composition isadministered enterally or parenterally.
 28. A method of preventing ortreating a condition caused by insufficient intake of polyunsaturatedfatty acids comprising administering to said patient said composition ofclaim 22 in an amount sufficient to effect said prevention or treatment.29. A method for producing a polyunsaturated fatty acid comprising thesteps of: a) isolating a nucleic acid sequence comprising orcomplementary to a nucleotide sequence: iii) encoding a polypeptidecomprising an amino acid sequence having at least 90% identity to anamino acid sequence selected from the group consisting of SEQ ID NO:2,SEQ ID NO:4, SEQ ID NO:6 and SEQ ID NO:8 or iv) having at least 90%identity to a nucleotide sequence selected from the group consisting ofSEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:5 and SEQ ID NO:7; b) constructing avector comprising: i) said isolated nucleotide sequence, ii) an isolatednucleotide sequence encoding an elongase and iii) an isolated nucleotidesequence encoding a Δ5-desaturase; c) introducing said vector into ahost cell for a time and under conditions sufficient for expression ofsaid Δ6-desaturase, said elongase and said Δ5-desaturase; and d)exposing said expressed Δ6-desaturase, said expressed elongase and saidexpressed Δ5-desaturase to a substrate polyunsaturated fatty acid inorder to convert said substrate to a product polyunsaturated fatty acid,said product polyunsaturated fatty acid to another polyunsaturated fattyacid and said another polyunsaturated fatty acid to a final productpolyunsaturated fatty acid.
 30. The method according to claim 29,wherein said substrate polyunsaturated fatty acid is linoleic acid, saidproduct polyunsaturated fatty acid is γ-linolenic acid, said anotherpolyunsaturated fatty acid is dihomo-γ-linolenic acid and said finalproduct polyunsaturated fatty acid is arachidonic acid.
 31. The methodaccording to claim 29 wherein said substrate polyunsaturated fatty acidis α-linolenic acid, said product polyunsaturated fatty acid isstearidonic acid, said another polyunsaturated fatty acid iseicosatetraenoic acid and said final product polyunsaturated fatty acidis eicosapentaenoic acid.
 32. An isolated nucleic acid sequence orfragment thereof which hybridizes, under moderate or high stringencyconditions, to a nucleic acid sequence selected from the groupconsisting of SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:5 and SEQ ID NO:7. 33.An isolated nucleic acid or fragment thereof, which hybridizes, undermoderate or high stringency conditions, to an isolated nucleic acidsequence encoding a polypeptide having desaturase activity, wherein theamino acid sequence of said polypeptide has at least 90% identity to anamino acid sequence selected from the group consisting of SEQ ID NO:2,SEQ ID NO:4, SEQ ID NO:6 and SEQ ID NO:8.